At the risk of starting a religious war, I'm curious: what operating system do you use? Are you a Linux freak? Stick with Windows, since it's what was installed on your machine? Or are you a Mac lover?
For the record, I love Mac OS X, especially since version 10.2 came out. When I compare it to the Windows 2000 I'm forced to deal with at work, the Mac is such a well-engineered piece of work that I find myself inventing excuses to use it instead of the Fujitsu crate sitting on my desk.
But then again, I'm biased. I've been Using Apples since I saw the Apple ][+ in 1979...