Get vista home premium 64. STOP SPREADING STUPID RUMORS. I have not had a single, NOT 1, game that will not run on my 64 bit OS. Even diablo 2, made back in 2000 runs on vista 64. DO YOUR RESEARCH.
The only reason to ever run a 32 bit OS is if you have an old craptacular 32 bit cpu.
A 32bit os can read up to 4GB Total, not 3.5gb or 3.2gb or whatever.
The cards have their own memory, but the system still reads only a total of 4gb, so if you got 4GB of system ram and those GTX cards in SLI, you will only have 3GB system ram available, because 1Gb is reserved for the cards.
SLI does not add up video ram, two 1GB cards still come out to being 1GB total.
Woops silly me. I'm just so used to saying 3.5gb because of most people having 512mb gpu.
But is the memory in SLI addressed? I knew it wasn't used but I thought windows still addressed it.