Whilst I agree with the sentiments of it's lame to want to know, or indeed, what's the real reason you want to break into word/excel documents, I use a program called "Advanced Office Password Recovery"
http://www.tucows.com/preview/281159
It's very good, and usually takes less than a few seconds to come up with the answer.
HTH!
You don't seriously want to know what your presents are, do you? How old are you??
Go on - you can tell us the real reason...
