To give a level playing field between the two VMs, I'm going to run the numbers on my MBP between these two. Just running the demos though, I can already say that Parallels 3.0 is orders of magnitude faster in running through the 3dmark demo ERROR-FREE, whereas VMWare Fusion seems to slow down during some parts of the demo and the audio gets really fuzzy.
EDIT: the 3rd test in 3dmark seems to crash parallels consistently
EDIT: the 3rd test in 3dmark seems to crash parallels consistently