It would help a lot if you posted a screenshot of what you are seeing...or at least post what the message says (that stops you opening the program/file).
I'm sure some of the tech savvy users got a bit of a laugh at this one :D, sorry lizzie :o
I'd try moyjos's recommendation and give Open Office a whirl
http://www.openoffice.org/
Who knows, you might even like the free alternative better!