As far as I know, all unix/linux have command line. In our datacenter (I work for trading company), I never spotted any GUI on unix, only command line.
I'm learning with unixacademy dvds. It is...
Install it on its own system, don't try and dual-boot -- if that goes sour you could lose everything. You don't have to put it on a "good" system, even a junk PIII makes a good home-server if it has...