[Alug] Looking for a low-end Linux server

I'm looking for a low-end linux box - preferably rack-mount to act as a secondary disk mirror for a large web site. Spec should be: - 512MB RAM - 750MHZ - 1GHz - processor not too important - at least 400-500GB hard disk space Does anybody have any idea where I can buy such a beast? I'm happy to do the linux install myself, as long as the box is linux-capable. Many thanks...