Honestly I haven't had one application that wont run on XP. The only problem I ran into was a driver issue for a scanner which was resolved my installing the XP driver.

What I find is that most apps that dont run are pretty darn old. I mean honestly if you are running some old VB exe app or something that came out during the win95 win3.1 era you really need to consider upgrading. It amazes me how much industry oriented apps (banking, payroll etc) are built on VERY old technology. I understand cutting costs, but some of these companies (and I mean pretty large big money firms) need to seriously update their software. Some of this stuff is built on technology from the windows 3.1 days. Unbeleivable.