1.4.Auto-Detect Windows User Names and Passwords and Windows Domains

We have a code that connects to a HTTP proxy that requires NTLM authentication. Currently we ask the user for: 1. Username 2. Password 3. Domain We would like to automatically detect this information and not ask the user. This is the username/password/domain user used to login his/her computer. In short, we want a code that will allow us to login the NTLM proxy without asking the user to provide authentication information, but obtain it from the operating system.