For word processing, I have to admit MS Office 2004 (Word) is the solid program. Actually, Office is the only program I would miss among MS products if MS disappeared.
I can work on my Mac and save it under normal Word file (.doc) and I can sent it to my PC via email and I can open it without any problem nor formatting issues. I can send the same file back and forth between Mac and PC as I edit the work.
Page is good as a quick and easy layout program (using InDesign CS2 for all layout jobs is sometime over-kill); but, I just don't feel that is a good "word processing" program per sé. Page is rather slow for fast typing and I often get annoyed with this lapse. I expect any word processing program to keep up with my typing without any delay. I don't like slackers for my word processing jobs.
Keynote is excellent presentation program. It gives fresh air in the corporate world in "me-too" PowerPoint slides.
If money is not too much of an issue, investing in Office 2004 is a good way to spend the money, in my opinion. It's important to note we often write or create reports so that someone can read them. If you are using some "non-standard" word processing program, your readers (who would be using Word, given the omnipotence of Word in the computing world) may not be able to open or read your messages. Or, formatting can be screwed up when the file is opened by your reader.