mandrake redhat and suse seem to be the 3 big ones for beginners, they with mandrake and suse leading the way in useability. but if you really wanna dig in and learn linux, try out debian or slackware or linux from scratch. start off with an easier distro untill you somewhat get into the swing of things, then when you're ready, dive in 🙂. thats what i did and i am enjoying debian much more than redhat or windows. (especially the latter 😛)