New rig

Is there any particular reason you picked a microATX motherboard. I would look for a nice ATX motherboard from Gigabyte or Asus. Here's a few suggestions:

GIGABYTE GA-EX58-UD4P LGA 1366 Intel X58 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128374

ASUS P6T LGA 1366 Intel X58 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131359

GIGABYTE GA-EX58-UD3R LGA 1366 Intel X58 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128375

GIGABYTE GA-EX58-UD5 LGA 1366 Intel X58 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128362

ASUS P6T Deluxe V2 LGA 1366 Intel X58 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131365
 


Because I'm dumb and only looked at the price

Edit: I fixed it with that cheaper Gigabyte as a placeholder
 
Also, should I go with the 4890 (free HAWX, too) or should I get the GTX 275 if I am gaming on 1280x1024 (starting out, I should be able to buy a new monitor a couple months after) and eventually on 1680x1050?
 
yeah but he can oc it himself and he's probably get just as far with the xfx than with the sapphire.

And you get a free game with the sapphire too, thats always a bonus.

but if you want power then get a GTX 275 and oc as far as possible since they get upto 15% fps increases when oc'd and are beating the 4890 already.
 
CUDA allows you to use CUDA based programs.

You might be interested in arcsoft which is a CUDA based program which upscales DVD quality to HD but otherwise it makes no difference to the average consumer.