CrunchBang Linux 8.10

CrunchBang is very nice for smaller machines, I have it running well in a 200 MB for example. For those who don't like the black theme, and want a more GNOME/Windows like 'start/apps menu', this is fairly easy to achieve without config file hacking - there are some more typical themes available as part of the standard installation, and a widget you can install to create menus from the panel.

The CrunchBang community forums are also very helpful and friendly, as well as the Ubuntu community.

The biggest benefit of an Ubuntu-based light distro is the vast range of apps and good security updates - so you don't have to give these up even if you have a low-end machine.