My experience with stuff like Sun VirtualBox is that even with the OpenGL integration it's pretty much unusable for any sort of graphical programs (3D modeling, video editing, games, etc. - and those are really the only programs for which there are no good Linux alternatives - what a shame). Maybe VMWare is better but VirtualBox is right up there with the best as far as I know. And keep in mind you have to have the resources (especially RAM) to fully support 2 operating systems and whatever programs they may be running.
Another option would be to run Linux and put Windows in a VMWare image.