login to multiple domains on same IIS server with same ASPNETDB members database?

basically I am building two websites (2 IIS sites) on the same win2k3 server that are utilizing a shared ASPNETDB members database. this was auto generated by visual studio w开发者_StackOverflow中文版hen integrating a login control, I'm sure you all know what it is.

The problem is that these 2 sites are working together and want a login on either site to server as a login for both sites.

so for example, user1 logs in (with asp.net login control) to domain.com, then navigates over to domain2.com - instead of requiring the user re-log-in on this domain, they should already be logged in (shared Profile.username parameter, same user from ASPNETDB)

I am a novice and have no idea where to begin with this or even how to best phrase the question (hence my inability to find help on google)

Read about Single Sign On:

http://msdn.microsoft.com/en-us/library/ms972971.aspx

http://msdn.microsoft.com/en-us/library/dd577079.aspx

http://www.codeproject.com/KB/aspnet/SingleSignon.aspx