A Closer Look at SLI and 8800M GTX Performance
 

After further consideration, we came up with several areas that we would like to investigate further. First, the WidowPC notebook shipped with Windows Vista 64-bit installed; that's definitely not a problem, but we didn't have the time to install the 32-bit version to see if there was any difference in overall performance. So our first request was that AVADirect configure a system with a 32-bit OS. Let's make things clear: considering they are shipping a system with 4 GB of memory, we definitely think a 64-bit OS is the way to go, and AVADirect does support (and recommend) such a configuration.

http://www.anandtech.com/mobile/showdoc.aspx?i=3262