Probably you may try the following clean solution :
1. Take a snapshot of programs, settings and files using one of PC migration tools.
2. Make a clean installation of XP on the whole disk space.
3. Recovery a snapshot on a new image.
The solution takes only personal part of your PC. That personal part can be recreated on any PC running the same or even higher version of an operating system . You may store it for upgrading to Windows 7.
I am familiar with 4 tools that are able to do transfer existing program, settings and file transfer
* PCMover - transfers about 250 programs, settings and files, about $50.
* Windows 7 Migration - transfers about 30 programs, settings and files, about $25
* Windows Easy Transfer - transfers operating system and program settings and files only, but free.
* PickMeApp - transfers about a million programs only, but free.