http://wiki.windower.net/guides/move...hout_reinstall
it's only painless if you're going from the same type OS to OS, like 64bit vista > 64bit vista/win7
if you're going from 32bit to 64, you'll have to edit the registry file to add in the wow6432node, but if done right, this whole process should take however long it takes of you to install POL and copy files from your backup to your harddrive and then you can be up and running (if your backup is updated).
I can upload my registry if you want, since you don't have your old system to pull it from.