Open up System > Library > CoreServices > Menu Extras. Control-click PPP.menu and choose Show Package Contents. In the window that opens, go to Contents > Resources > English.lproj and open Localizable.strings.
In the TextEdit window that opens, replace "Open Internet Connect…" with "Open Internet Explorer…" and "Internet Connect.app" with "Internet Explorer.app". Quit TexEdit and save changes. Restart.
After you restart and login, click on the PPP menu and choose Open Internet Explorer…. IE should open!
[Editor's note: Please make a backup of anything you modify before you start!]

