looks very nice, Seagate is very good , dont change it , (although i like WD too ) , if u can afford 8800GTS 640 ,then go for it , but for resolutions lunder 1600x1200 , 8800GTS 320 is fine and is equal to 640 in many games
Looks pretty darn good. I'm with Maziar -- I wouldn't change out the Seagate either. For the budget you stated, the 8800GTS 320 is probably about where you need to be.
If you want RAM with MicronD9 chips, there's currently a mail-in-rebate on Crucial Ballistic on newegg that brings the price down to $62.99 for 2GB. I'm not sure if the GSkill is D9. But then you have to deal with whether or not you get the rebate, which can be troublesome at times.
Other than that, you might be able to save 10 bucks on the case (with a Coolermaster Centurion 5) and $25 on the CPU HSF (with an Arctic Cooling Freezer 7 Pro), but there's certainly nothing at all wrong with the ones you've chosen. Good build!
I think I'd still go with DS3R. It has better onboard audio, better components, RAID support, and you can have more than 4 SATA devices. Of course, if you have a soundcard and only 1 hard disk/1 DVD and don't care about RAID and you intend to get a new motherboard in two years or so anyway then all these advantages are useless.
Overall, a good system. You could save $150 to $200 by going with a Pentium E2160, and o/c'ing it 3.2 - 3.4 GHz. Then use the savings to upgrade the video card to a 8800GTX. Gaming performance would be significantly greater.