depends on the game I guess. From what I heard, VPC is reallly slow. So I wouldnt count on it.
“If you are neutral in situations of injustice, you have chosen the side of the oppressor. If an elephant has its foot on the tail of a mouse and you say that you are neutral, the mouse will not appreciate your neutrality.” Bishop Desmond Tutu
I have never done it but have heard nothing but bad news regarding this. Virtual PC is fine (if not slow) for running your average programs but you will not get acceptable performance running a recent game.
More specifically, virtualization or emulation, like Parallels and Virtual PC respectively, currently don't offer any hardware run 3D support. Thus, any games that require 3D rendering for graphics, will NOT run fast at all. It's like playing your games in Software Rendered mode.
Mind you, games like Solitaire as mentioned above, are 2D, and will run fine.