I'm sure you'd get as many different opinions as people you ask, but here's
something to think about.
As a grad student you are of course able to get the student/teacher version
of Office 2004 for the Mac. It runs about $149 and allows three licenses
for three of your computers. Some universities offer this even cheaper
depending on their arrangement with Microsoft.
My alma mater did not offer the Mac version at a discount, but they DID
offer the full PC version (2003) for about $20 including FrontPage.
I had an old PC and ended up buying the PC version but already had the Mac
version too. I greatly prefer the Mac version for working, but there are a
few tiny things that simply will not work on the Mac version. For example,
I ran across certain custom scripts for Excel that were written in Visual
Basic and they would not run on the Mac version. In addition, some of the
effects in Powerpoint such as motion paths are not in the Mac version, but
will run there if created on a PC.
95%+ of what you do can easily be done in the Mac version. Only you can
decide if it is worth that occassional headache to enjoy what I think is
superior software. Personally, I'd do it just for Entourage.
Good luck,
-Mark