From what I read is that there is no quad SLI out yet, Nvidia has not even made a bridage SLI connector for the 7950GX2 has well has drivers that will support them. Has of right now the 7900GX2 is just a stand alone card. This was done before with Asus with the two 7800GTs
IMO I wouldn't go with a beffy video card at this time since DX10 is coming out, and DX10 games will be out on the market faster then it took ppl to go from AGP from PCI-E.
I'm making a system with a Conore E6400 or E6600 the video card that im going to have with it is going to be two or maybe just one 7600 GT KO 256MB or 7900 GS KO. 256/512MB
They will be my starting cards until the direct DX10 cards come out
http://www.tomshardware.com/2006/06/...orce_7950_gx2/