Using Group Policy to enforce an internet proxy server

Many networks of significant size use a forward proxy server to filter their internet traffic. This is essentially a box that sits near the edge of the corporate network; whenever client computers in the network try to access the internet, their requests are sent out through this server. Doing this enables companies to monitor internet use, restrict browsing permissions, and keep many forms of malware at bay. When implementing a proxy server, one of the big questions is always, "How do we enforce the use of this proxy?". Some solutions do a default route through the proxy server so that all traffic flows outbound that way at a network level. More often, though, it is desirable for the proxy server settings to be configured at the browser level because it is probably unnecessary for all traffic to flow through this proxy; only the browser's web traffic should do so. In these cases, you could certainly open the Internet...