I have to agree with NJ5 and Squlliam on Vista stability. We have only one customer that uses Vista for their business, and I get far fewer support calls from them than any of my other customers (who run XP Pro). Also, none of their Vista computers have ever had a virus or crash in the two years I've been working with them, while the one XP machine they have has had two viruses.
IMO, the only thing that was lacking with Vista was performance (runs great on a beefy system, not so great on a basic system) and compatibility. I believe MS has addressed both of these issues with 7.