Re: Just ordered the parts for my new build!
Dude, power has a lot more effect than brand...
A 4850 is going to smoke a 9800, simple as that. Now a game that is optimized for Nvidia will perform better than its Ati competitor, the 4830, but it isn't going to beat out the 4850. Both antec and corsair are great psu brands. A 520W antec is a lot better than a 400W corsair. Now, if you upgrade your gpu, you will need a new psu as well because it is so weak. If I were you, I would just send those parts back when they come and go with the better setup.
CPU: Intel Core i7 920
GPU: ASUS STRIX GTX 970
Ram: 12GB 1600 Mhz DDR3
Mobo: ASUS P6T
PSU: 750W PC Power & Cooling