Well, I can officially say that I'm a Mac fan as well.
I'm using a Mac mini Core Duo, and it's lightning fast, even the browsing speed in Firefox is literally 10x faster, with GTP loading in a split second. There's a ton of cool features, like it has it's own media center you can control with a remote, the dock of course, and everything on Windows is better on here. Sure, it's harder to find programs, but I love it. It's just cleaner and faster. And efficient. I can't hear it making noise to save my life.
As for what I use...
Internet Browser: Firefox, it's faster, and there's extensions and themes.
IM: Adium, and MSN Messenger, but I'm still deciding what to choose. Adium because it supports multiple IM systems, and there's the duck

, and Messenger for it's simplicity.
Music: iTunes, all the way.
Video: Quicktime and Windows Media Player, but I'll try out the Flip4Mac thing and possibly ditch WMP.