2x4850's or 2 used 4870's if you can find em for sub 200$. if you must go nVidia get 2x8800GTX's they can be had for sub 200$ easily.like others say the 4850x2 will be out soon i would wait for that to drop and get it while it is hot, will be a bit more gracious to you're cases space and you're PSU.