I've been using Foresight Linux on my PC almost exclusively, and I love it
http://www.foresightlinux.com
It's based on rPath modular architecture. Read about it here:
http://www.rpath.com
Although I believe Ubuntu is about to make a huge leap on April, when version 7.x is released, I think I'll stick to Foresight, becausel I love the package management system (Conary), which I believe is far more advanced than any other package manager currently available. That includes apt-get, yum, and even FreeBSD "ports" mechanism.
Read about Conary here:
http://wiki.rpath.com/wiki/Conary:Concepts
Note: Foresight is a GNOME based desktop, so if you want KDE, then Foresight is not for you!
However, if you want a system that hardly breaks, even when doing:
sudo conary updateall, which updates ALL the system and binaries, then Foresight might be just for you

After installation, Foresight leaves you with a beautiful Desktop, ready with most office utilities, full wireless support, sound and excelent eye candy (Compiz, and Beryl available as a package)
Give it a try
-kwag