If you love Ubuntu, but wanted a lightweight version for your older computer, then WattOS maybe what you are looking for.
WattOS is a new lightweight Linux distribution that has low power requirement and can be used on computer with older hardware. It is in fact, a stripped down version of Ubuntu, with many of the heavy-duty applications such as OpenOffice removed, and/or replaced with a faster and smaller alternative.
According to the developer, there will be three desktop versions:
wattOS – The core desktop system using a fully featured Gnome desktop
mWattOS – A smaller desktop system using XFCE as the core interface.
µWattOS – An even smaller desktop utilizing a minimal desktop GUI or command line. Ideal for appliances, small systems, kiosks, or old computers.
Substation – A server edition
At the moment, only the full version of wattOS is available for download. Not much detail is known of the mWattOS, µWattOS and Substation yet.
WattOS is still in alpha stage and there are still plenty of work that need to be done. Meanwhile, you can download the source file at WattOS Download page.