Let's not forget, if you have the bandwidth and the drive space, there are several versions of Linux that will install on a Windows vfat filesystem. Although I'm not sure this is what you're looking for, PhatLinux and WinLinux2000 both will install on a Windows machine without reformattting or anything. Of course, the downside is you can't run the two simultaneously like you can with VMWare, which I use. The thing to remember with VMWare is the more RAM you have, the better. I run it on a PII-366 laptop with 128 MB RAM, and it's a little pokey (to be kind) but useable.
Also, there is an effort to port many Unix/Linux programs to windows with U/Win. You can read about it here: