Budget 512mb graphic cards....

Im looking to upgrade my mobo to a sli compatible board. i want to get dual 512mb graphics cards, but i dont want to spend that much. i have seen 2 nividia options using the 6600 chipset (Diablotek NVIDIA GeForce 6600 / 512MB DDR2 / PCI Express / SLI and the XFX Geforce 6600 / 512MB DDR2 / PCI Express / SLI), and ATI has 3, two use the 1300 chips and the other uses the 1600(HIS Hightech H130H512N Radeon X1300 512MB 256-bit GDDR2 PCI Express, and the SAPPHIRE 100145 Radeon X1600PRO 512MB 128-bit GDDR2). they all run around the same price, so thats not an issue. whta im looking for is the best performance. im leaning toward the x1300 b/c it has a 256bit memory, although the processor speed is alittle slower. all the other cards have 128 memory, and have the same or slightly faster processors. which do u think will be better as i play games that use lots of texture (like Doom 3, HL2, and GTA:SA)?

btw. each of these cards cost between $120 and $150.