Thanks J.C for the Link. I used it to create a little helper class.
public class HttpHelper : IHttpHelper
{
public KeyValuePair<string, string>
CreateAuthorizationHeader(ICredentials credentials)
{
NetworkCredential networkCredential =
credentials.GetCredential(null, null);
string userName = networkCredential.UserName;
string userPassword = networkCredential.Password;
string authInfo = userName + ":" + userPassword;
authInfo = Convert.ToBase64String(Encoding.Default.GetBytes(authInfo));
return new KeyValuePair<string, string>("Authorization", "Basic " + authInfo);
}
}