Hi
I think can answer your questions, there is a few options you have. First off been hunting forever for a board that can due sli/crossfire; they due exist but there is a catch of course.
First the board your talking about was made by Evga and is still for sale on ebay but not retail. It only supports sli in a 8x mode and 939 which is not the most ideal processor anymore.
Now boards that due support are exclusive shuttle boards. Shuttle makes a 975X (yes bad *** chipset) board. Heres the catch you have to buy the complete bare bone system which runs 400 bucks, yay ouch! They also have a system already built with crossfire cards and everything but expect big bucks!! The board has 2 16x pci express slots and fully capable of supporting crossfire and a core 2 duo. Only thing sucks about this have to tear the board out and as far know will fit in any other micro case. Sorta a waste and pain but hey at least its custom =). You could also just use the shuttle setup but the psu is far from power pushing and the case, lets just say leaves much to be desired.
They also make a nforce 4 board with full 16x sli but is only 939 board and a 570 ultra chipset board but only has one pci-e slot.
Why shuttle does not retail these boards honestly dont know but its the only option you got for going dual video cards on a micro. Also might want to do some research. When I was first building my micro my 7950 use to shut down from heat; even with a zalman cooler could only get it down to 60C under load which was little high. I was forced to liquid cool it!! Now thats a weaker end card in todays market and was only one!! Plus sli and crossfire really are over kill, have yet to face a game the 2900xt cant handle solo on max settings. Also the abit board with 630A chipset has out performed a 680I board with a core 2 duo. Sometimes 2 doesnt always mean better (voodoo found this out the hard way), yeah it may look cool but can you honestly justify needing 2 8800 gtxs? Unless you work in grahpics its over kill. Also the micro really cant handle the heat or power needs on it, unless you have custom installed a 700 watt'er with help of a dremel like me =). The only way can think about controlling temps is with liquid cooler and that opens up whole new mess. Guess its just the price you pay for mobility.