Basically, if I am changing the MoBo, everything goes....I might save a HD for use as an external, use an optical in new box but that's about it.
My 1st four considerations are:
-What does the person want to do w/ it ?
-Where does he / she wanna put it ? (Fit question)
-What manufacturer's experiences does he / she have ?
-We talking big video cards ?
Lacking any specific direction, I'd start w/ a full tower case, if someone finds that "too big", I'll drop to a mid tower but nothing smaller. Usually my 1st case choice is Antec as they can be flashy / conservative with a flip of a switch (turns off LED's), great telephone tech support, and also being able to buy a PSU from the same vendor minimizes cabling and support issues. Current fav's are Antec 1200 and 902 w/ Antec Signature series PSU's. If it has optional fan mounts, they get bought. If they want something more aggressive in styling, I recommend the HAF 932 w/ the Corsair HX PSU's.
Next is the MoBo and, again, lacking any specific direction, I'll first look at Asus' offerings .... again reason is live telephone tech support as well as long familiarity w/ their BIOS'. About 90% of my builds "in this millenium" have been on Asus boards. Current fav's Rampge II Extreme and P6T. But as with all choices, performance has to be in the top 2 % or I'm bye bye. And I always go for feature laden boards rather than their budget alternatives as the price incremental isn't worth installing whatever is needed later. Built two machines for brothers, one with on board firewire and one w/o and within weeks had to install a firewire card on the 2nd one. But again, whether to go feature rich or bare bones is a personal and budgetary choice.
CPU is picked solely on budget but I don't do AMD builds. While AMD seems to have the best bang for the buck in many instances over the years, most of my builds are CAD boxes and budget usually isn't an issue. Current fav, best i7 budget will allow.
Memory is picked to match the board, usually 2 notches in DDR speed above the rated MoBo speed to allow for future BIOS revisions and some headroom. No fav's but usually gonna spring for fastest CASS timings. Currently that's Mushkin Redline but I'm free from any brand loyalty and will buy from any major vendor whomever is top dog atm.
Opticals I always leaned to Plextor but now that they have dropped their 2 year warranty, and farm out production of many models to others, they've been knocked off their "always buy" perch. Now I depend on the reviews and currently my choice just happens to be the BR capable Plextor 320AS.
CPU Cooler again is a "reviewer's choice" thing and right now I really like the Prolimatech's both for their extreme ease of installation and their top notch performance. It goes on w/ IC Diamond 7 Carat Thermal Compound.
For GFX cards, I'll 1st look a the offerings of the MoBo manufacturer if for no other reason than to cut off that 1st level tech support dude at the MoBo vendor who has been taught to say "it must be your vid card" (yes, the vid card TS guys has been taught to say "It must be your MoBo". But again, it's a numbers game. Beat my current choice by more than 2 % and you're history.
Hard Drives - Here I peek at THG performance charts and pick the one at the top in most charts though I do weigh sound and temperature high. Generally that's been a Seagate 7200.12 drive of late.
Finally GFX cards .... this is a tough time to choose GFX cards as pre Xmas a new generation hits the stores. Rev A hardware will be followed by Rev B and Rev C as the kinks get worked out and as this is going on, the manufacturer's are coming out with their own "non reference design" tweaked hardware. Each side ups the ante a bit until, like last season we will finish with this 2010's equivalent of the 4870x2 and 295 GTX. It's that last part of the curve that I prefer to be on. At this point, I think these are the best choices at 1920 x 1200:
Twin 5850's w/ dedicated nVidia card (say 9800 GT) for PhysX processing - The $620 solution is about $20 higher than the upcoming 5870x2 but should give well more than enough frame rates while still allowing you to enjoy PhysX effects. $740 for twin 5870's is just too big a number. Installation of an nVidia card along side ATI hardware requires a hacked driver patch available by following the link here:
http://www.tomshardware.com/news/nvidia-ATI-physx-patch-gpu,8786.html
If ya don't give a hoot about PhysX, drop the nVidia card and save $100
The GTX295 ($470) remains attractive for those looking for a single card solution solution where it's still the "top dog" or for multiple monitor usage w/o the hassles, or for those who have more interest in PhysX than DX11. If ya just looking for frame rates though, twin 5850's will give you more than the GTX 295 for an extra $50 or so.
Under $400, it's hard to argue against the 5870, again, unless PhysX strikes your fancy.
Below that, I suggest going to the THG performance charts an picking a card in your price range.
If ya don't know what PhysX means to gaming then I'd suggest the following review over at Firing Squad as an introduction:
http://www.firingsquad.com/hardware/batman_arkham_asylum_physx_performance/
"Banners and flags flutter and sway, shredding when a Batarang or gun fire hits. Caution tape and cobwebs tear as Batman moves through them. Sheets of paper are strewn about the floors throughout Arkham interiors. They furl and roll around in reaction to characters kicking them. During combat, Batman’s swift movements cause them to fly into the air and float back down again. Without PhysX, they only exist as static piles and textures stuck onto surfaces. On the outside, fallen leaves act in much the same way, adding to the appearance of your interactions with the game world.
Eye candy PhysX features like cloth simulation and volumetric smoke/fog are nice additions that really up the immersion factor, but it’s the addition of rigid bodies that really sets Batman: AA apart from previous PhysX titles like Mirror’s Edge. You can really see this in the scarecrow levels where entire walls can be blown up into hundreds of pieces"
Again, that kinda thing may or may not tickle your fancy so choose accordingly but the "patch" makes the technology available to both camps, at least for the moment. There's about 150 games which are PhysX equipped. It's harder for me at this point to get excited about DX11 which is supported in only 10 released and / or upcoming games and where most of what is talked about is DX10 compatibility.
http://thehobbylounge.com/forum/index.php?topic=6056.0
"Along with the pipeline changes, we see a whole host of new tweaks and adjustments. DirectX 11 is actually a strict superset of DirectX 10.1, meaning that all of those features are completely encapsulated in and unchanged by DirectX 11. This simple fact means that all DX11 hardware will include the changes required to be DX 10.1 compliant (which only AMD can claim at the moment). In addition to these tweaks, we also see these further extensions:
While changes in the pipeline allow developers to write programs to accomplish different types of tasks, these more subtle changes allow those programs to be more complex, higher quality, and/or more performant. Beyond all this, Microsoft has also gone out of its way to help make parallel programming a little bit easier for game developers.
Rather than throwing out old constructs in order to move towards more programmability, Microsoft has built DirectX 11 as a strict superset of DirectX 10/10.1, which enables some curious possibilities. Essentailly, DX10 code will be DX11 code that chooses not to implement some of the advanced features. On the flipside, DX11 will be able to run on down level hardware. Of course, all of the features of DX11 will not be available, but it does mean that developers can stick with DX11 and target both DX10 and DX11 hardware without the need for two completely separate implementations: they're both the same but one targets a subset of functionality. Different code paths will be necessary if something DX11 only (like the tessellator or compute shader) is used, but this will still definitely be a benefit in transitioning to DX11 from DX10.
We are especially hopeful about a faster shift to DX11 because of the added advantages it will bring even to DX10 hardware. The major benefit I'm talking about here is multi-threading. Yes, eventually everything will need to be drawn rasterized and displayed (linearly and synchronously), but DX11 adds multi-threading support that allows applications to simultaneously create resources or manage state and issue draw commands all from an arbitrary number of threads. This may not significantly speed up the graphics subsystem (especially if we are already very GPU limited), but this does increase the ability to more easily explicitly massively thread a game and take advantage of the increasing number of CPU cores on the desktop."
The relevance of DX11 will change over time and I don't expect DX11 to be the big flop that DX10 was. Still 2-3 years from now it's impact could be significant and if you keep your GFX cards for a long time, going DX11 now will be more important than for someone who changes cards every 12-24 months.
Again, the easy, no fret choice is to get a "carry me over till later" card and wait till February's Intel price cuts and use the money saved from the winter price reductions on a new card or set of cards. The mature products from the new generation will be in the channel and any super cards will have been at least announced if you still want to wait. By then, even more PhysX and DX11 titles will have been released and we'll all be able to see just what DX11 and PhysX brings to the table....and we'll also be able to see what nVidia brings to the table.
If ya can't wait, it's a safe bet that neither will "sweep the table" and any of the above choices should easily get you through a year or two of satisfied gaming.