My small business is now hiring; is this an adequate contract?

I've been trying to keep it very simple, but am a little afraid of mismatched legalese. Is this a valid contract to offer? Am I being fair? (This isn't really the usual startup thing, I'm mostly looking for part time workers to do assembly, testing and field support ).

http://robots-everywhere.com/re_wiki/index.php?title=Operative_Handbook