Just stay away from Nvidia and you'll already be doing at least 10 times better in almost all cases.
Yea, I figured that out after posting and right when I was about to post my new card choice you replied
I found a ATI 5770
Those aren't too bad.. For the price anyways.
Those are good for the amount of power they take and can easily reach 200Mhash/s without OCing too much. How much did you find them for?