AMD64 is still superior. The AMD64 OMC + DDR400 beats the P4s with DDR2-666 at the same price point.
Well you are wrong, it is not. Can you buy AMD64 dual-core CPU for $250?!? Right, you can't! I hope you won't argue that single-core AMD64 is better than dual-core Intel when it comes to Photoshop?!?
While I agree that sometimes you can get better results with AMD64 and DDR400 it is only if you use EXPENSIVE DDR-400 or better. Since he can't afford it, it doesn't make any sense.
You should use 2 DIMMs regardless.
I am using 4 DIMMS and I don't have any bandwidth issues, With Intel memory controllers neither latency nor command rate depends on the number of modules used so there is no reason not to use all slots.
@tjhva:
7600 GS and GT have 128-bit memory interface. GS has 800MHz DDR2 and GT has 1500MHz GDDR3. They also differ in clock and number of active fragment and vertex processors. 7300 is a cheap solution which can have some local video memory and for the rest it uses system RAM hurting the overall performance. Moreover, it doesn't have certaing video postprocessing features which supposedly lift some burden from the CPU. I would advise you to get at least 7600GS.
As for Raptor, only getting 150GB drive would make any sense. Since you can't afford it, getting regular drives is the only option.
I would usually suggest to get two drives as you said, but since they are going for $93 making two of them $186, you may want to consider
WD4000YR for $182 -- it is definately faster (65 MB/s buffer to disk sustained) and better drive featurewise. Although you get less space then with 2xWD2500KS you get 5yr warranty and you can add one more later to form matrix RAID if you decide to get Intel board with ICH7R southbridge, or just get another smaller drive for system and use this one for data.
Corsair Value RAM DD400 runs fine and performs well.
S939 and S940 are still very good platforms. They are available now, stable, proven, fast, upgradeable, reasonably priced and can match or beat any Intel CPU on the market today.
In fact AMD's 90nm parts beat the 65nm P4s in performance and heat dissipation.
http://www.linuxhardware.org/article.pl?sid=05/02/24/1747228&mode=thread
http://www.anandtech.com/linux/showdoc.aspx?i=2163
http://www.intel.com/performance/desktop/extreme/em64t.htm
http://techreport.com/reviews/2006q1/fx60-vs-955xe/index.x?pg=5
You still have to slow down to use more DIMMs.
DDR400 is cheaper in many cases.
It doesn't matter how fast the Raptors are the poster cannot afford it.