Office is completely interchangeable between Mac and PC (the files that is.) If you are just doing day-to-day business stuff either machine is equally suited. The software is there for a Mac (although not in as great quantity for PC) to do whatever you want to do. The greatest limitations are video games and CAD software - for either of those, I would go to a PC - otherwise, it is really preference. Macs are easier to use and install software for than a PC. If you want a cross-compatible database setup that can publish to the web, use FileMaker Pro. You can run it on Mac or PC.
Macs aren't really limited anymore - anything you can do on a PC, you can do on a Mac. Most people just don't know that becaus they don't use them. I manage a network of 30 Unix servers from a Macintosh laptop, write documents in word, email them to my PC-toting counterparts and have no problems.
Give it a try - it make take a week to get used to the differences but overall I think it is a better computing experience.