Go with the Nvidia, just cuz it doesn't say HD in the name doesn't mean it's not HD, and it is an HD video card, with CUDA and PhysX programming capability, not to mention it's high performance just as the ATI card is, and both r from XFX, which is a kickass company. Also, why does he want a Thermaltake Tsunami if it's just gonna be for graphics rendering? I understand the desire for fashion along with function, but that chassis is over $100 for the non-windowed one alone, including shipping. I second the dropping from 8GB to 6GB, unless he wants more RAM, in which case u can get away with 12GB if you drop the Tsunami to a less expensive chassis. With what u have, getting the best of what matters most, dropping the 8GB to 6GB (3x 2GB) you're still over budget by 98 before rebates are taken into effect and u get ur rebates in the mail. If you drop to a lower-priced chassis, then that helps to squeeze some juice, but not a ton. Figure out whether or not the mail-in-rebate offers matter or not, cuz most of the time they go thru fine, tho a few months later is when u get ur cards (yeah, like a debit card), sometimes they get lost in the shuffle n u never see anything.
XFX GTS250
ASUS P6T
Thermaltake Tsunami
Intel Core i7 920
Antec TP New TP-750
Seagate ST3750528AS 750GB
Win7 UE 64-Bit OEM for SB
Corsair XMS2 DDR3 1600
I'm fairly certain you can calculate on your own somehow, so I'll leave that up to you. Honestly, if he can be talked out of the Tsunami, then go for it n get a much better priced one. If you have a Micro Center close by, they have the i7 920 on sale for $229.99. Also, i note that you haven't selected an optical drive either. Last key component to figure in. Go with a lower cost chassis n it'll help u figure that into the budget as well.