How can I use the browser on the ISA Server to access the Internet?
Configure the browser to be a "pseudo" Web Proxy client. In the browser proxy configuration dialog box, use the server name "localhost" (without the quotes). Why do I call it a pseudo Web Proxy client? Because this works even if you have no Protocol Rules in place to allow outbound access to HTTP! Test this out right after you install ISA Server. Do not configure any Protocol Rules and configure the browser to use "localhost" as the Proxy.