iWork is fine once you adjust to it - I'm formatting my wife's PhD thesis in Pages and it creates breathtakingly beautiful pages with little effort. It is the first word processor I've used on which styles actually make sense, in which they work like the human brain does. In NeoOffice I spend half my time fighting the styles, in Pages they simply work.
OTOH NeOffice is free - there's no reason not to have it on your hard drive. Pages does not read or write .docx or .odt files at the moment. Which is crazy - they are XML-based schemes just like Pages' own format and conversion should be child's play. My only other complaint is that they should sell the apps separately, as they do on the iPad: I NEVER use the spreadsheet. The somewhat pricey Bento from Filemaker is a good companion program for iWork.
BTW, if you use Keynote on your iMac but your presentation will be on a non-Apple computer, let Keynote generate a Quicktime .mov file for you. Of course this means you will have to install Quicktime on the PC, but once that is done you can show off those Keynote transitions even if you don't have an Apple laptop.
For email I just use the Mail program that comes with OSX. But I belong to the respond-and-delete school of email use - no archives of spam messages going back fifteen years for me. In the extremely rare event that an email is worth preserving, paste it to Evernote.
EDIT 6/09/2010 : with the latest update, Pages will read .docx files but not save them. Haven't tried .odt yet.