Another great thing about virtualisation rather than dual boot is portability. You can take your virtual machine with your Vista setup and copy it across to any other PC at any time and run it there. Great when it comes time to move to a new PC in the future.

You even have portability between platforms. I have a WinXP VM set up just how I want it for my CD ripping (set it up years ago with dBPoweramp et al). It was originally created in VBox on a Windows Vista host machine, since the it has run on various different Windows host, a couple of OSX hosts and it now runs on my Linux server.