Everytime I try to apt-get update it comes up with the following:

Err http://archive.ubuntu.com Precise/main amd64 Packages 404 Not Found [IP: 91.189.91.14 80]
Err http://archive.ubuntu.com Precise/restricted amd64 Packages 404 Not Found [IP: 91.189.91.14 80]

What am I doing wrong?