I just switched to Firefox last week, I'm not really sure what I think about it though. I mean all everyone pretty much says about it is all the customizing about it. Theme-wise they don't have any Cubs/Colts or movie related themes that I like. As far as add-ons go, on my IE browser I have the tabbed browsing, my toolbar is the best, it's got spyware scaner, weather, cubs, google search spot, and many others so I'm kinda having a hard time liking it. So for all you Firefox fans, let me know if there's anything really worth switching over for.
As for Linux goes, I tried it once on my last PC and I just didn't like it. Not to say it's a bad program it just wasn't for me. I much rather prefer my Windows. Granted Vista is nice, but it's gotten more complicated. I'd much rather have my Windows 98 Second Edition to me the best OS ever made.
Ohh also the kid who helped create Firefox was 17 when he started on the project.