Howtogeek posted a guide about assigning a static IP address to an Ubuntu 10.04 desktop computer

If you have a home network with several computers, assigning them static IP addresses can make troubleshooting easier. Today we take a look at switching from DHCP to a static IP in Ubuntu.

Assign a Static IP
Using Static IPs prevents address conflicts between machines and can allow easier access to them. If you have a small home network and are satisfied with the machines getting their IP address automatically via DHCP, there won?t be anything gained by using static addresses.

  How to Assign a Static IP to an Ubuntu 10.04 Desktop Computer