Sooner or later, every administrator finds himself wanting to run applications from multiple operating systems on the same physical machine simultaneously, and then struggles to figure out a solution that works somewhat seamlessly.

Maybe you're married to Microsoft Exchange, but you secretly pine for open-source email tools like SpamAssassin or fetchmail. Or maybe you're using UNIX-based applications for some network services, but you really want to run them under Windows so you can integrate them into your overall network security model. Whatever the case, wishing that you could run best-of-breed applications from different operating systems simultaneously is pretty common, and often unavoidable.

In my case, I ran into this situation when upgrading an aging utility server, and I made the mistake of buying a brand-new Intel motherboard that does not yet have adequate Linux driver support. If I was going to use this system at all, it had to run Windows, but most of the software that this particular system is meant to run was designed for UNIX.