I know there are some illegal alternatives to purchasing the software, but even downloading a keygen program runs a high risk of getting a virus. I don't recomend it for that reason.
Personally, I just stick to Wordpad. It has everything but spellcheck, and it comes standard on all computers that have a version of Windows for the OS. If it becomes neccessary to use spellcheck, I go to a website that has a forum with spell check, copy past the wordpad text to the forum, use spell check, fix the errors, then close it without posting.