I tried the software Jim linked to. Here's what I found out. I tried to convert a locked (password protected document). First, because it is a long document (300+ pages) it crashed. I tried again, just reading 5 pages. It didn't crash, but it crashed WordPad, and WP when I tried to open the converted doc. (I'm not a Word user) When I tried converting just one page it crashed the same programs, and while Works word processor opened it, there was nothing there. Conclusion: If a PDF has been locked, it probably won't convert.
Before I dumped the program, I decided to try it on a one page document with no locks or password protection. There it did just fine. Conclusion: it will work on open documents, but locked ones probably not.