If you're going with AMD, there's no point in going nVidia for the GPU if you want SLI. Most of the AM2+ and AM3 boards only have support for Crossfire and not SLI, so you can go nVidia, but keep in mind you won't be able to SLI. There are a few of them that do support SLI, like the Foxconn Destroyer, but they are a bit more pricey.