Windows to Linux

I'm thinking about switching to Linux. Specifically Ubuntu or Fedora. Anyone want to tell me why or why I shouldn't? Currently using Vista Home and I like it but I just want to see what else is out there. Plus if its more secure, thats always a plus.

A friend of mine has installed Linux on his laptop and we sometimes play Windows games on it. It appears to work perfectly, but I'm still a bit hesitant to make the jump myself.