I have a web based product that is only open to staff of various very secure corporations. Most of these organisations use Windows XP or server 2000, some using products like Novell laid over the top, to control user log in. Signing in once allows users access to all systems in each corporation (Single Sign On - SSO). We are trying to find a way that will allow those users to be automatically logged in when they wish to access our website when they are at work, using their SSO. The website is SQL Server. Access is via Forms Authentication. The site is asp.net. Is this achievable through Windows, and if so, how?