Unless you're running at an extremely high resolution, a single 8800GT should be fine. However, if you want SLI, you need an nForce-based motherboard.
Most SLI motherboards out there are fine, but the likes of eVGA, XFX, and BFG have been associated with video cards, not motherboards, so they may be unfamiliar to you. They are perfectly fine as many companies with nForce boards use the nVidia reference design, which has typically proven to be a fine set up.

I don't know if you'll need a 3rd party cooler, as the 8800GT's use a smaller manufacturing process than the rest of the 8800 series.