I can make my VM on my iMac (2gb ram 2.4 duo) play games at decent settings.
Have you set it all up right?
Paralells looks great, but at the time I got VMware cheap becuse of a friends licence ect. If I were to but any at full price I would have done the Bootcamp route.
I have tried bootcamp and Paralells, and I do prefer Paralells, however I would reccomend VM because of its massive forums with loads of people that will help you if anything goes wrong (Which all 3 will).
I'm trying to put across both sides of the argument, so I don't sound like a bias n00b, but I think that VMware is best for somebody that isn't gaming. I use it for VB work abd to test programs out on, and it works above + beyond the COD for it.
There's very little in it atm.