What would (or did) it take for you to switch operating systems?

The other day while I was covering Steve Jobs' keynote speech at WWDC 08 I was sort of half expecting him to announce a new MacBook/MacBook Pro line. With this thought came the idea of making a much bigger commitment to Mac OS X than I've made so far.

As it turned out Steve didn't announce any new MacBooks so I was let off the hook, but it did make me wonder something - What does it take (or did take, for those who have made a switch) for someone to switch operating systems?

• So, what is it? If you were going to leave your current OS for another one, what would make you do this? New features? Security scares? Ease of use? Change being as good as a rest?
• If you recently made a switch (and that applies to distro switches for Linux users), what was it that prompted you to make the switch? Was the switch painless or painful? And, most important of all, was it worthwhile?

The more progress I make to becoming OS-agnostic (though I'm more than willing to admit that I have a long way to go on this front), the more I come to realize a few things:

• No OS is perfect.
• Neither Mac OS X, Windows XP/Vista nor the big-name Linux distros are as bad as some people make out.
• Everyone should run more than one platform because it gives you perspective.
• I can never see myself switching back to a single platform (even if this was Mac OS or Linux, because that would just be a case of shooting myself in the foot, part II).
• I wish I could virtualize the Mac OS (really, seriously, what is up with not being able to do that?).

Shoot!