Ok, sorry for the lack of a true Mac item, but people interested in virtualization might find this interesting anyway. I installed the newly free-ed Microsoft Virtual PC 2004 on an unsupport Windows version (at least it is not listed as supported in the Microsoft downloads area): Windows Media Center Edition. I decided to try to install Microsoft Visual Basic 2005 Express Edition (also free) on Windows 2000. So, I found a copy of Windows 2000 Professional Edition and the Service Pack 4 disc for it and installed it under Virtual PC 2004.
The installation went fine, but the various security updates required three passes and three reboots. Lots of downloading and waiting. I also had to find an Internet Explorer 6 disc and then upgrade it to SP1 as required by Visual Basic 2005 Express Edition. At this point, I shut down the Guest OS and made a copy of the virtual hard disk to an external hard drive. After the various reboots and, I think, just shy of 500MB of downloads (I opted to install the documentation and SQL Server Express too), I appear to have a working instance of Visual Basic 2005 Express Edition in my little sandboxed Windows 2000.
Windows 2000 Professional running as a Guest OS under Virtual PC 2004 installed on a Windows Media Center PC
The process should be more or less the same using Parallels Desktop for Mac on an Intel-based Mac (see my review of it at Parallels Desktop for the Mac). So, go forth and virtualize, folks :-)