Why are you building another rig, for someone else?? If not the one you have right now is good enough, what CANT you do with that. Heck im running on an AGP 6800gs and I think its fine, I can run doom 3 on high with AA on. If your building another comp though regardless just get a 7800gt or a 6800gs PCIE card. SLI=ripoff, it's been shown that it really isnt even close to doubling the graphical power, 30% at the best of times. It makes more sense to me to get one 7800gt or gtx and later on when you can upgrade forget about getting another one to SLI them, just ditch the 7800 for whatever is new at that time. From benchmarks I've seen 2 6800gts still isnt as good as 1 7800gt or gtx.