From my experience Vista has terrible compatibility issues with a lot of drivers. Even if your computer does pass the vista readiness test, it doesn't insure you that everything will go smoothly. After installing vista on my laptop I couldn't get my video driver to work after trying for 3 days. I finally gave up and reformatted switching back to XP. If I were to ever get vista, it would be on a new computer that came with it pre-installed. Upgrading to it has caused nothing but problems for me as well has a few of my friends.

And yes, Ubuntu is pretty sweet.