I like AbiWord for word processing, and it deals with MS Word files just fine: http://www.abiword.org/download/ . Besides, if they're plain MS Word documents, TextEdit can read and write them just fine!

And I prefer two buttons on my mouse as well -- so I use a MacAlly two button mini-mouse on my iBook (though any USB two button mouse will work, really, even those from Microsoft): http://www.amazon.com/exec/obidos/tg/detail/-/B00006HMQY/102-1567196-6216918?v=glance