*butting in* I used to use Open Office and beta for someone who used Word. She writes a lot of restricted word count shorts. Open Office always said more words than Word did! However, having said that, it's usually different by only about 100 words, so I really wouldn't stress about it at all.

I now use Word because when a publisher requests an rtf file, Open Office is a bitch and deletes all the formating all the time.