Microsoft's MS Proxy and GetRight|
MS Proxy needs a little more configuration on the server side:
MS Proxy Server has 2 authentication modes, Basic and Challenge response.
GetRight uses the "Basic" authentication mode. BUT, in order for Basic authentication to work, you need to give the users "log on locally" rights to the Proxy server machine. For Challenge response, you do not need this right.
Giving the internet users group that right should make GetRight (and many other programs that do just do Basic proxy logins) work properly with Microsoft Proxy.