As much out of curiosity as anything else, a few weeks ago I installed Virtual PC on my old ThinkPad T41 and although I only set up a single W2K VM and have hardly touched it since, I've noticed that the machine is now much less responsive.
I've eliminated the possibility that malware is causing the problem, it really does seem to stem from the time I installed VPC.
Should Virtual PC cause this? I notice there is a bug that makes it difficult to remove (not very confidence-inspiring...) so I need to look into that so I can uninstall and see it it makes any difference. However, Windows being Windows I'm not 100% convinced that an uninstall may undo whatever VPC seems to have done.