Originally posted by: CP5670
The two 7900GTs are faster, but you also have to deal with all the SLI compatibility problems. Both options are bad at this point in any case.
The Two 7900GTs are faster only in higher resolutions, average res's the improvement is hardly worth double the price, and for double the price you can get a 8800GTX.
For the author of the thread, here is an article that you will find very useful:
7900 series and SLI review
After reading this my suggestion is spend your money according to what you need, if you play hardcore all new games in high resolution get a 8800GTX or ATI equivalent.