[Ryan O]

Are you behind a firewall of some kind? If your browser is set up to connect through a firewall, Eclipse may not be able to do so unless it is specially set up. The fact that you cannot connect to some of the standard Eclipse download sites indicates an IDE-level problem.

Have you ever been able to update this installation of Eclipse from your current machine? (Aka biggest info needed is whether this is a change or has been a problem since day 1 of using Eclipse, this will help figure out the specific issue occurring)