Linux is a very good and stable OS. There are many different flvors of it you can get.. one of the easiest ones to use is Mandrake. While its a great OS.. its meant more for server load then the normal PC user.. the reason is becauase alot of applications currently for windows wont run on linux.
There isnt a subscription for it.. you just buy the software and you are good to go.
Lindows is different. Lnidows actually allows you to start up a linux environment while you are in Windows. So you would technically have two Operating systems running at one time on your PC. I have seen someone use Lindows before and it was really cool
I just havent gotten around to getting it either.