I totally rely on my WinXP vm to run Office legacy stuff, an old scanner for which I only have XP drivers, and to keep alive accounts used by my daughter when she was little. Perhaps I should update it to SP4...
Edit: It was a p2v vm of a desktop I started running in 2005. By 2009/10 it had started to crawl: 5m+ for boot and shutdown compared to seconds as a vm on Linux!