After installing Software Update Services (SUS) 1.0 w/SP1 on my Windows 2003 Standard Server w/SP1 I was unable to view the SUSadmin webpage. The error message
"You are not authorized to view this pageYou do not have permission to view this directory or page due to the access control list (ACL) that is configured for this resource on the Web server. "
To fix this, navigate to Default Web Site-->SUSAdmin via IIS Manager and change the authentication methods for the SUSAdmin site to use Integrated Windows authentication. Refesh the SUSadmin page and you should now see the admin site.