well the memory needs to be fast like ddr3 or gddr5 not ddr2
the GPU clock speed should be in rounf 600-900mhz
a good gfx card is http://www.ebuyer.com/product/151334
well it is a GPU so the amount of memory is only part of it. the speed and clock speed (like in your cpu contribute to it ) also buy a new one as older ones are not DX10 compatable also you may not need an i7 if you are buying it for the DDR3 memory you can get ddr2 @ 1.15GHz like me look @ my spec al my parts were great also do you want a photo guide from when i make mine