Windows 7 - How to move Virtual XP to a new Installation (RC - RTM)

"Windows XP Mode creates a differencing disk for each user. This way, it only stores the changes that each user makes compared to the original parent hard disk. If you want to access that disk, you need to reinstall the Windows XP Mode beta (or at least extract or copy the VHD file that it contains).

There is no smooth upgrade path from Windows XP Mode beta to RC (and presumably to RTM), so you will have to reinstall your programs in Windows XP Mode eventually. However, reinstalling the beta will at least allow you to recover any files that are stored on your Windows XP Mode differencing disk."