Linux V5.2 versus V6.0

Since I am a long way from an actual CNC machine or a conversion I thought I could at least get my feet wet by becoming familiar with Linux. One of the things I have picked up by lurking is that EMC is compatible with the V5.2 but not the latest V6.0. It also seems that the V6.0 has improvements that make it a little more user friendly and easier to install. So my question is, should I try to find a V5.2 or should I just go with V6.0 and hope that EMC will be updated to run under V6.0 in the forseeable future?

I've seen RedHat V6.0 for $60; I seem to remember that this OS was originally a freeware product. Am I wrong or what happened to that concept?

Regards,

Steve Barmash
Newbie 1st Class