128 or 64 MB?
I have the 128, and it overclocked rather easily. You should be able to run 300 Mhz core easily, some go up to 330. I run 310 to be safe. RAM overclock on the card depends on the model, but my 128 MB card runs fine at 525. Some 128 Meg cards can hit 550 or even 600 Mhz, but again I stay within a "safe" range. I added a bit of extra cooling in the form of a slot fan that extracts air from right below the video card. If you have the 64MB card, I think you can run 600 Mhz RAM easy.
Other than that, I just crank it to max quality. It's got more than enough power to run max quality and still be fast.
