Proxy Changer

Proxy Changer is a windows program that runs in the system tray and allows you to quickly change between proxy servers, or to quickly change proxy settings in Internet Explorer.

Simply setup proxy servers in the program and set one as default and one as an alternate to be able to quickly switch between them.
Proxy Changer can also enable and disable proxy, set to automatically detect settings, or to use the automatic configuration setting, all from the system tray within a few clicks.