in which case
take a ghost of the image. I have a clone of my hard drive (74gb Raptor) on my File HD (250gb)
if ever anything goes **** up i can just restore the disk file for file how it was. Best thing about it, its done using windows own total PC backup built into vista so 100 % legal
but you can achieve the same result using Acronis True Image / Norton Ghost or similar.
oh and for what its worth, the dual boot as a recovery tool would be useless, as none of your changed would be mirrored. You'd might as well just keep a backup of your files and reformat.