Some virtual system's aren't too bad. It's not near the same as a regular system, but I had my computer running Vista under XP and I could watch videos and all on the virtual Vista system without any problems.
As for another OS, someone's apparently recoding Windows XP. I forget the name it's going by, but it looks quite promising thus far!
I ran it on a P4 with 1Gb of RAM and shared 512Mb with Ubuntu and it was good... Just on a laptop were the CD speeds are restricted, you might notice it being laggy when running from the LiveCD...