Why reinstall the driver anyway? No need, it's the same driver, unless you're upgrading to a new version, but that has nothing to do with changing hardware.
glxgears output doesn't mean jack, anyway, I had a K6-II with a GF2 that had a higher glxgears fps than my Opteron + Quadro! Run a game to see if 3D is working properly. Quake 3 or Doom 3 timedemo is a better indicator than glxgears, you can download a demo if you don't have them.
That said, 1000 does seem a bit low, make sure glxinfo indicates that DRI is enabled and working.