I would give the 177.41's a shot if you are looking for beta drivers. They perform excellently. You could also try the 177.66's. Other than that, try the latest WHQL ones on nV's website. Its a crap shoot when it comes to drivers though, usually. Its best to try a few drivers and see which perform best for your particular setup.
If you are looking for a place to grab these drivers, check out www.guru3d.com .