Essential System Administration is by far the best unix book I've ever come across. Comes in very handy very often. Edit: if you're doing system administration - if not,
Unix Made Easy is a slightly better beginners book and a decent reference - I'm always digging in it - it really is a good reference for the basics - I've installed various unix-like utilities on most Winblows machines I've used, WinVi32 being one of my all time faves.
I'm pretty sure you can still get SunSolaris for free or close to it. Try doing a search on the dreaded
www.sun.com (I used to work for SGI - Sun Micro was our mortal enemy) for "download Solaris". I think freeBSD was already mentioned. Pretty sure they both have a nice GUI, although I actually haven't used freeBSD.
All the unises I've used have had some type of GUI. HP-UX, Irix, Solaris, and the various Linuses. Getting it working over a network sucks up bandwidth though, so it usually isn't done. You wouldn't need it on a server, since it's not a 'customer'-type machine - that's probably why you didn't see it. Your university probably has at least one lab with a bunch of Unix workstations that run GUIs(might try the Engineering Dept. - windoze doesn't usually suffice for what they do).
WRT Free Unix Distro, found this:
http://www.sun.com/software/solaris/...es_program.xml
- may Bill Joy smile upon you