Arch is really good. It has a package manager called Pacman (
http://wiki.archlinux.org/index.php/Pacman). It takes care of dependencies
for you. Where Arch shines is that it install a bare bones system with no
GUI at all. You need to add whatever you want to make it work. It is getting
down to the bare bones of Linux. Their documentation is among the very best.
There are also community maintained repositories (AUR), like Ubuntu PPAs.
However, at this time you can only update from Arch's own repositories. Many
users would like to have updates to AUR installed applications, so this may
come down the road. You should not attempt to install Arch unless you have
patience and a willingness to learn from the commandline. It takes time to
set it up, but once it is working it is rock solid and fast.

I would also recommend Zenwalk which is Slackware based and works for
beginners to advanced users. Slackware is one of the oldest Linux
distributions (1993) that is popular among universities. Zenwalk is one of
the simplest Slack distros. If you like Slack then Vector Linux might work
for you, too. Both Vector and Zenwalk have GUIs and graphical installers.

If you want something that is fast, but more mainstream then try PCLinuxOS
(comes in 32 bit only). If you want more then do a search for optimised
Linux distributions.