MS has discontiniued Word as a single product I believe the cheapest way to get it is with MS Works which is total crap.

OpenOffice is great but if you find it too large and you're only after a word processor then you could always give AbiWord a try. Although both of the aforementioned are 90% Word compatable I do recommend downloading MS Word Viewer 2003 which is free (as in no $) for viewing the final 10% of documents that won't display properly in the alternatives.