C#/HTTP Auth

hi, i want to make a small game server watch/admin tool(like hlsw but with better admin features for unreal tournament). my problem is how to connect to the unreal webadmin, it requires a http authentication(a dialog pops up when you connect via browser). it was no problem with php, you can enter the username and password into the url. but how can this be done in c#? im using the WebClient class but i cant see something about authorization there...