It seems like the only weakness of the 320MB version is the 8800GTS was the amount of memory in large texture games, so SLI would fix that issue, do you think it would be a better option then a single 8800GTX assuming 1920X1080 is the max resolution. so better AA and AF will come from an SLi setup.
I don't know why everyone is so crazy about SLI. Yes in theory (and for bragging rights) its cool but it won't get you double the performance. Some will say, depending on the chipset, you can only see around 120% increase. Go with the single GTX and when you feel the need, you have another slot ready for the 2nd.
i have SLI currently(and yeah it was for bragging rights, though i do get about 70-80% performance boost), but i didnt know about the 2nd memory not being used. I dont need exotic resolutions, just 1280X1024 and 1920X1080 and those not at the same time. Regardless i cant upgrade until nvidia puts out good drivers for vista x64 as my computer ended up with a deleted registry and a courrupt boot sector as a "freeware" utility cleaned my registry and so i installed vista instead.