I have been playing with linux on and off for 5 or 6 years now. When I look back at where it was when I started using it, it has come along way. There still may be some peripherals that don't work right after install, but it seems like almost anything can be tweaked to work fairly easily.
It is more secure, and has become much much much much more user friendly. Would I recommend somebody who has only used windows their entire life switch to linux cold turkey? Absolutely not, but I would recommend n00bs go download Ubuntu Linux. You don't have to install it on your system at all to try it out. You can download it, burn it to a disc, and boot/run it from the cd without installing. That way you can get familiar with it without installing it and can decide for yourself if it's worth installing in the future.
I recommend booting from the disc vs. dual boot for n00bs simply because it's too easy to screw things up if you don't know what you are doing when partitioning your hard drive.
I know others probably don't like Ubuntu because you like other distro's of linux instead, but it's gotta be the easiest version to use for those without any linux experience.
Oh yeah, and the best reason to use linux....it's FREE!!!!