I'd give iLife 08 a good look if you are wanting something similar to Office (as long as you don't need Entourage). $109 gets you a bloody good WOrd processor/page layout app, a new program called Numbers which is like Excel on speed (wicked stuff) and Keynote which blows PowerPoint out of the water everytime! Everytime I run a Keynote people always ask "how can I do that in Powerpoint?", I take great pleasure in letting them know they can't!
The real kicker is you can import and export to the Office suite of software as well as many other formats such as PDF, HTML, RTF, Flash, Quicktime movie...the list goes on!
Save yourself $500 and get iLife 08!