Case : I never liked mid towers... Juts do ur self a favor and get a full tower. You won't regret it. + its more future proof.
MoBo : U DONT NEED! X48 especially if u not going SLI get a P35 or an X38
VGA : Good card, I have the same thing. Very Very soon the new cards from nvedia will be released (I believe sometime in June) so u can ether get a card from EVGA and then just do a step-up or u can wait for a bit longer and just get the beast. But if u not a HARD CORE Crysis gamer 9800GTX is a beats and should be great!!!
PSU : Looks good
CPU : hmm well it looks decent. I personally have Q9450 it has 12mb catch and just a notch faster default timing of 2.6Ghz (im sure there is more 2 it) but if u budget is very tight then stick with what u have, if not then spend an extra $100 and get Q9450
RAM : This RAM looks good, I don't know if u like to OC, but if u do, 1066 instead of 800 might be better, just a thought
(and dont wory about getting a mobo that has 800 standar memory and runing a 1066 memory in it, it will work! thats what i gat)
HDD : Can I just say a VERY nice purchase
I have 3 of this bad boys and they are great! These suckers have dual platters, which makes them fast! you will love this HDD!!! If u want to take it a step higher, get a 2nd one and do a raid 0! That's what I gat. Dont buy in to the 32mb cache HDD, the WD6400AAKS are still faster! because of the dual platters.
CD drive : Looks good
OS :
What ever u do, DONT GET XP 64 bit, I don't know if u know this, but its worse then Vista 32 or 64!!! Vista just has a bad rep man. I personally was an XP user for about 8 years, 2 month ago I switched to Vista Ultimate 64 bit and I love it!!! Just get Vista man, u will be fine!
ps; + rep me if that helped, thanks
Cheers