Well, the 1st problem is you're going to run an AMD setup.

I think the Intel chips give you better performance for the money. Which doesn't seem to be an object, given your choice of graphics cards.
If you're looking to run SLI, that mobo is a Crossfire board. AMD cards only in multiple configuration. I'm not sure Asus has released the latest 3/4 card SLI boards yet.
The 8800GTX's will run in up to quad sli mode on the right mobo if you can fit them on. 780i Northbridge for Intel chips, 680a MCP for AMD's.
With the amount of hardware you're looking to run, I think at least an 800W power supply is in order, if not a 1000w. The AMD processor and 8800GTX cards suck up a lot of power.
Good luck.