You can only access the shared drive on an Airport if you know how to set up the firewall or if you subscribe to Apple's Mobile Me service ($59 a year).
With a Mac (Not MAC, by the way. MAC in all caps means something else and calling a Mac a MAC only confuses networking people) you get iLife which gives you a webpage writing app, a class-leading photo organiser, iMovie for editing movies and Garage Band for recording and making music. You also get iChat (an AIM- and Gmail-compatible chat app), an email application and a browser. What you don't get is a word processor, spreadsheet or presentation app, but you have the choice of buying iWork (Apple's office suite) or Microsoft Office. Or, of course, you can go like the modern kids and use Google's free online apps for words and numbers.
Also, if you insist, you can buy VMWare, which allows you to run Windows at the same time as Mac OS X, if you have a Windows license.
Stuff you don't need: Anti-Virus (not yet, anyway. I doubt you'll need one for at least a year, either), Anti-spywear (same as AV) or backup app (built-in to Mac OS X 10.5).
I run servers for a living. I've been a systems administrator for over a decade and I've managed large Windows LANs in my time, but these days mostly manage Windows and Linux web and application servers. At home, I have a MacBook and a Mac Mini (plugged into the TV) and the missus has a MacBook as well. At work, I have one of the most powerful Macs you've ever seen (lots of Xeons, 9GB RAM, 2x24" HD displays ...) and I can run copies of my servers in virtual environments on my Mac simultaneously without a slow-down.
Macs aren't perfect, but they get in the way of what you want to do a lot less than Windows PCs.
Oh, and here's me being controversial, they're not that much more expensive. Yes, you can get cheaper laptops, for instance, but you can't get an equal laptop for the same money, or if you manage, you'll be saving $100 at best.
If you want a PC to play games, get a Mac and an Xbox.