Microsoft Office 2008 for mac has to be the single worst piece of office software I HAVE EVER USED. If you ever set up "spaces" don't even bother installing that garbage.
Use IWork, it is wonderful.
I would buy from the Apple store and go through the education store:
http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore.woa?routing=eduind&cid=AOS-US-Edu-EdMkting-01162009
I would also buy the new 13 inch Macbook Pro, with 4 gbs of ram and a decent hard drive. The new OS, Snow leopard, is being released in September for $30. It will be lightning fast with the 4GBs of RAM (A New Utility in Snow Leopard called "Grand Central Station" really uses the most amount of RAM possible to make things fast).