Yeah, I just priced out a tower build using i7 920, 6GB, X58 motherboard, 1TB, 1 DVD burner, 700W OCZ PSU and 2x 4890XXX CFed and it came out to be ~$1600 before taxes. This should be able to run it at 1680x1050 with 4xAA and have no problem, but it's going to be a noisy monster.
http://www.techpowerup.com/reviews/A...ossFire/6.html
And by the way, please don't buy a computer from Best Buy. Go get NCIX to assemble one for you.