> - my web.config authentication mode = 'Windows' (<authentication > mode="Windows" />)
Assuming that you have NTLM auth to make windows auth mode for .net, the problem is that the server has no password to do the login api for a network call to another server. You will most likely find that basic auth works, but ntlm doesn't. It doesn't matter what you run the server under if you are doing windows authentication. If you get kerberos auth working (use a support tool called kerbtray to help), you could get this working internally. Otherwise use com+ would be my best suggestion.
