I can happily say I am glad I bought the 8800GTS 512MB card. I paid just nder $300 for it and it plays everything I throw at it @ 1920X1200 with some AA/AF thrown in. While the GX2 is of course a fast card, it is nothing to lose sleep about. I could simply add another GTS to my system for roughly $275-300 (Thank you XFX price drops) and match the performance for less money.
In my opinion, even 2 9800GX2's will not allow high res Crysis at very high details/settings. In fact, I am wanting to see if they can even get Quad SLI working this time since they never released an official driver for the 7950GX2's as it didn't work.
Here ya go, Quas SLi 9800GX2 review.............