I want to fit Survey Project into a larger installation that has its own authentication. It is enough like Windows authentication that if I could get that working, I think I'd be OK.  But when I search on the forums for problems with or tips for using Windows authentication, I find nothing.  And when I use Google to search I find posts which are both years old and unhelpful.

I tried adding the ASP.NET security addin to my survey but when I tried to log in with my Windows credentials the login failed (the login page said "Invalid Login. Please try again."  If this is easily done in SP as it stands, I'm reasonably OK with editing login.aspx.cs to do something if FormAuthenication.IsEnabled is false, if that's the right place to start. Any clues welcome.  Thanks.