http://www.theultimatesteal.com
For anyone who will be enrolled in any accredited college or university program this fall, Microsoft is making Office 2007 Ultimate available for $60, or $70 if you would like to have a physical media.
I participated in this program last year. It is really worth it to get all of the Office applications for 10% of their normal cost.
Microsoft will reopen the program on August 20, 2008 (same day as a lot of universities begin class).