I've used OpenOffice Writer before. It's plenty capable on its own, but it's just not good enough at data exchange with Word (which is the same reason I'm not using Wordworth for everything on my Amiga). Luckily, I've had the good fortune to have not had to pay for a Microsoft product in ages - good old right-place-right-time for site-licensed copies - and this has held up for Mac Office 
You might have an upgrade path. In the past Microsoft allowed users to cross upgrade from one platform to another. You might check to see if its available. I've recently had problems with exchanging files with PC users using a 2004 Office for Mac version. Since it's my freelance work, I guess I'll need to update Office myself. I'd love to use the free versions, I just don't want to explain to clients why they have problems with my files!
Actually, going back to doing work for Amiga companies, file format has been a big hassle. I bought my first Mac so I could produce an Amiga manual. The client was much happier when I switched and, since I had a second computer to write on, their buggy software didn't cost me work time!
