By definition Linux must be free. It is required by the open source distribution liscence. What they charge for is fast download, cd's, support, etc.
Go to Redhat, Mandrake, etc websites and look for the free downloadable version. It is there. When you find it, it will give you a list of mirrors. One of those was a state university in the upper midwest (forget which one) it was the best mirror.
The distro's vary in size but figure 3 to 7 CD's. Doing the math that is gonna take a while.
I did the downlaod of both (mandarake and redhat) last spring. They both worked fine on a crappy old K6 machine. The one installed more easily (I think it was Redhat, but can't swear to that).
Do some research first to make sure the brand you pick supports all your hardware (i.e. has drivers).
