Crossover etc, is a pita. So is dual booting. I run linux as my base, but have an actual winXP license running as a virtual machine. Now we're cookin' with gas.
My friend was demoing me his system on the weekend. Mac laptop with a big widescreen attached. Had it running as a dual moniter setup, with the laptop screen running his mac stuff, and the monitor running windows inside a virtual machine. Mac here, jump up, there's your windows box. Way cool.