In Microsoft Word 2003, it was possible to store different Versions of a Document inside the Document itself (File -> Versions.. or check here -> Chapter Implementing Versions). Somehow, I'm missing this feature in 2010. Is it still available or was that feature kicked out of Word?
Sorry to have to bring you the bad news, but it's been a while since MS did away with this feature. In the recent releases of Word, the only such option is for recovery if word crashes in between; in this case you can go to: [File -> Info -> Versions] to access the unsaved work.