VirtualPC? Not Universal yet, and why would you need emulation, when you can us virtualization?
Parallels Workstation should be available soon enough. You would still be installing Windows though; but you'd run it within a window on Mac OS X, as opposed to dual-booting. Running at the same time is much less hassle, though you'll want enough RAM. Anyway, you should only need to open it for whatever Windows-only applications you may need.