Parallels + MMORPG on the VM, then a full HD movie in iTunes, fullscreen, iMovie, and Handbrake both encoding, and a graphic intense game on the Mac. My top of the line iMac can't handle a VM and iMovie, so that would push it to it's limits. You might even have to force restart. Up to you if you want to try it, though.
Handbrake is free, and almost did it for me, along with iTunes email, ichat, safari, firefox, imovie, adobe photoshop cs4. It was pretty slow, I have a the newest iMac, with the lowest spec' and SL dev preview.... I'm going to format and reinstall SL though on FRI.