I selected Eclipse from within USC and clicked the 'Use this source' button. The 'Progress' icon whirls for a few seconds, and then I get a message box:
Failed to download repository information
W:Failed to fetch http://security.ubuntu.com/ubuntu/dists/quantal-security/main/source/Sources 404 Not Found [IP: 2001:67c:1562::17 80]
Why won't it download?