welcome to LQ!
By implication, you have a router connecting all these computers. In such a setup, I would always use dynamic IPs (DHCP), but that's another story.
In the router configuration, you have to assign an IP to the port that the Ubuntu box is connected to. Then in the network configuration on the computer, you have to enter the IP. you will also need to enter DNS information---check to see what is used on the other computers.
If you have any more problems.....
ping 188.8.131.52 ##(one of the actual IPs for Google) If this works, and the first does not, then it is a DNS issue.