I mean: Start windows. Do NOT log in when you get the login-screen (just press ESC). Now open the dialup dialog, and make the connection to the network. You will get a network-login screen (because you where not already logged in), and now you log in. It's a weird procedure I know but the network-script doesn't run if you're already logged in before dialing in.

I predict a loginscript in your near future...