The Biostars are proven overclocking champs when it comes to the AMD platform. Price/Performance, you can't really go wrong. Asus generally are fairly solid boards too, and I personally have a Gigabyte board.
Honestly though - since you have a GTX260, you should be looking at a 790FX+SB750 board instead of a 790GX. The 790GX has video built in, which will be useless to you. Also, you may want to wait about a month for the AM3 boards and chips to come out since you're making a platform change anyway. You'll likely get a bit more performance out of it for just about the same money (once RAM prices come down).