I've heard nothing but bad things from someone who was biased to hate it in the first place, whereas I've heard good things from a friend who was unbiased, and didn't care at first whether or not his new computer came with Vista or XP. Now he won't leave Vista, and I wouldn't either!

The simple truth is, if you get a computer with Vista preinstalled, with all the drivers and whatnot guaranteed to run smoothly, you have a 95% chance of a good experience. However, if you slap a copy of Vista on a computer that was built for XP, you have the same chance of an error-free installation as you do Linux.