I have installed HP-UX onto a virgin machine. Well, almost. Actually, I watched while a HP-UX guy did it (I was the sysadmin after he did that - it was my first HP box). Although you had to follow the instructions, it booted from a CD-ROM and was not difficult to do right. Maintaining the patches et al was very RedHat-ish, though, with the sysadmin required to manually download the patches from HP's website.

Wade.