Arch vs Ubuntu
Arch has a simpler foundation than Ubuntu. If you like to compile your own kernels, try out bleeding-edge CVS-only projects, or build a program from source every once in a while, Arch is better suited. If you want to get up and running quickly and not fiddle around with the guts of the system, Ubuntu is better suited. In general, developers and tinkerers will probably like Arch better than Ubuntu.
From the Archlinux wiki ( http://wiki.archlinux.org
). I guess I'm a tinkerer. I like to tinker with my system. Also, the AUR system is great.