Mandriva: Good Choice for Newbies
I installed Mandriva 2006 from a downloaded DVD onto a permanent Linux partition on my Pentium 4 machine.
I've one slight concern with Mandriva's otherwise excellent installation procedure -- partitioning during the installation, rather than before, is not as simple a task as with, say SuSE's Yast2 installer.
Generally, however, setup is a dream. It's handled speedily and graphically, with guidance for newbies and lots of options for the experienced.