Windows: Many people have kept their old Windows XP computers running because they have software on the systems that can't be reinstalled. VirtualXP lets you migrate an existing Windows XP installation into a virtual machine that you can run on Windows 7 or 8.
We've covered how to run a virtual version of Windows XP in Windows 8, but that involves doing a clean install, which means you'd need to reinstall your programs and migrate your data. VirtualXP solves that problem by converting your Windows XP hard drive into a Microsoft virtual disk. Once it does the conversion, you can open it in Windows 7 or 8.
I tried the program and it worked great, except that Windows XP noticed the move to a new machine and wanted to reactivate. I couldn't reactivate Windows, but the programs I use worked fine. Your mileage may vary, but it's worth a shot.