you have asked for unix there a very little(or none) free treu-unix distributions but bsd and linux looks extremly much at unix. freebsd (is a bsd version the most user friendly version they sayed at in the book but it still isn't user friendly ) is a unix clone (less or more, it has unix code in it). and linux had been build from a scratch with the same free standards where unix is made from ( i completly forgot which three). but the biggest different between unix computers is the kernel. All the other commando's are more or less the same. But if you start with unix, start with linux that are the easiest to understand distrobutions. I it is you first "unix" computer try suse linux or redhat linux those are the most easy to install.
www.suse.com for suse linux homepage you can find a place where you can download suse there
www.redhat.com for the redhat homepage you can find a place to download redhat there.
in a good local computer shop there is a good chance that you can find linux there. the best way to learn it is to buy it and if you don't know anything read it in the book with is with it.
www.linux.com for many information over linux
www.freebsd.com for many information about bsd
[Edited by Neo on 01-06-2001 at 06:06 PM]