http://virt-dimension.sourceforge.net/
Even though there isn’t any active development on this (last update: 2005-07-09), this is still the best virtual desktop manager I’ve found for Windows. A couple quirks, but so far I’m happy with it. It lets me set up the same keys I use on Mac/Solaris for virtual desktop switching, will switch backgrounds, and even has a text popup of the desktop name when you switch. Its missing some features, but it covers the basics, which is good enough for me.