Install SiSoft sandra, and check to see if your other performance meters (CPU,memory bandwidth, etc) are where they should be. This can help make sure that the problem is in the vid card or the drivers.
If all else fails and you still can't get it working right, a clean install of windows followed by the VIA 4-in-1, and then your vid card drivers, might do the trick, but windows re-installs are such a pain in the ass that I hesitate to recommend doing so.
edit: One last thing. I've heard (although I haven't used one myself) that the Aureal cards (MX300) take quite a bit of CPU time. You could try pulling your soundcard temporarily and seeing if that brings your numbers up to where Anand's are.