Once again, thanks for everyone's input. It's interesting to hear the variety of experiences and opinions on offer.

In summary it looks like running Virtual PC on a server would have a resource impact when in use (CPU, RAM and DISK) and is perhaps not the optimal product to run on a server.

I only want to use Virtual PC very occasionaly for remote troubleshooting purposes. I already have RDP access to all the servers I support. As the servers are routinely upgraded and they will likely get 2Gb RAM, dual CPU and RAID 5 disk arrays at their next upgrade, I'm sure they can take the occasional resource hit although the customer may notice a slight drop in performance, but they will get problems fixed more quickly and would not lose access to a PC whilst work was carried out.

Educational price of Virtual PC is negligable (~£30 inc media) when combined with the cost of a new server. I've been using Virtual PC for several years now (since before Microsoft bought it from Connectix) and have never known it to crash the host PC even when I've had 3 or 4 guest sessions running.