Did you install VMware Tools in the virtual machine (e.g. is there a VMware-three-boxes icon in the system tray)? Another thing to try is to enable 3D acceleration under Settings (the virtual machine must be shut down, not suspended for you to change this).

It depends on which games you're trying to run. While the most demanding games certainly should be run natively, there are certainly some which run well.

djwini: Can you be more specific about which games you're interested in?

Finally got some time to try this. On my Mac mini running 10.5.4 and Fusion 2.0rc1, Enchanted Cavern ran very smoothly; Ancient Quest of Saqqarah was a bit choppy by playable. On a Mac with an actual graphics card (as opposed to the unsupported integrated video of a mini), I imagine it would run smoothly. Couldn't test Journey to the Center of the Earth as I couldn't find a demo version.