EDIT: solved

I've installed bitcoin and I'm now GPU mining in the deepbit pool and I've managed to get it to connect and everything, but the Mhash rate seems very low. I'm using a GTX460 and getting an Mhash rate of ~27 when it should be about triple that.

Using MSI Afterburner, I can see that 99% of the GPU is being used, but the core clock and shader clock are running at half the set speed. Anyone got any idea why this is so?