Re: Couple of ?
You can't use ATI cards with Nvidia drivers.
As for the PSU, I'd guess you'd probably want to go with a good brand that's around 700w minimum for a 8800GTX and GTX260
MSI MPower Z87 | 4770k | CNPS9900MAX-B | 8GB G.Skill 1866 | EVGA GTX760 |ThermalTake 850w | X-Fi Titanium | HAF | Asus PA248Q | Lycosa | Death Adder | Win8 Pro 64
MSI GD65 | 2500k | H50 | 8GB G.skill | GTX570 | Ubuntu 13.10
17" Inspiron | i5 | 4GB DDR3 | 500GB HDD | Win7 Pro 64