I already use Linux. Don't be fooled by it being free, I agree you can get the Kernel free but it needs a terrific amount of work to configure and set it up how you want and you need to know what you are doing. There are distributions that save all that but most of them you have to pay for.
I use Xandros Linux, it looks like Windows but that's where the resemblance stops.
I won't be going back to Windows by the way, my choice.