Knoppix
www.knoppix.net
I kid you not. After XP "lost" my dynamic disk mbr, the only way I could find all the files, and how they were supposed to be ordered was by using this.
If you don't know linux, it's still a small learning curve to get your stuff off.
Oh I should say this didn't fix the any problems in windows, but it allowed me to copy everything to another location and safely rebuild.