Unfortunately that is not possible with that type of program. There are too many fies dropped in other locations as well as registry keys that are added or changed.
Your best bet would be to try and get a Student/Teacher version. It is quite a bit cheaper than the standard edition.
If you don't want to do that, you can try what is called Open Office. It is a free word processor program, compatible with Word and Wordperfect..http://www.openoffice.org/