Give us a list of the primary applications you use and we can give you a yes or no.
Contrary to what the linux people say, it's not for everybody or every purpose. Personally I have linux, mac, and vista running on three computers next to each other... but I'm a geek. If I was going to recommend a non-Windows OS to somebody, I would probably suggest using a Mac, much more user friendly than linux.
That said, there's simply nothing wrong with Windows. If it works for you, don't feel ashamed of it. I'm well known as a geek, but I proudly run Vista and like it.
To condense down into a few points:
1) Heavy gamer - use XP
2) Mostly browsing, office and email - use Vista (if you have a PC), or a Mac
3) Running a server or an older pc - Linux
4) Programming - Programmers should already know what to use =)