If you're just trying to learn more about the topic please keep it to a single thread and ask any questions there. Having 15 threads covering various aspects of the same topic, such as recovering Word files, recovering lost pictures, recovering e-mails, etc just leads to confusion and potential deletions as duplicates.
On the other hand, are you actually, personally, experiencing each and every one of those problems? You mentioned not being able to boot Windows XP, not being able to access files through Vista, corruption under Linux, lost pictures, flash drive woes, etc. It sounds like you're dealing with massive failures on at least 6 different machines, if not more. Seems this is where the confusion lies...actually encountering errors and trying to fix them or simply learn for future reference. That's something best stated up front.
I don't know what you've covered thus far, but start by clicking here and branching out to all of the referenced articles at the bottom. That will give you a good foothold on the subject.