I followed the instructions in Windows-Authentication.rar which I downloaded from http://www.sitefinity.com/devnet/forums/sitefinity-4-x/general-discussions/active-directory-and-permissions.aspx
Upon completing the instructions, I was able to assign permission to Active Directory users in Sitefinity and the users could log in.
However, when going to the login screen users are presented with a dropdown containing 3 Authentication providers:
3. The domain name I specified in step 3 of the Windows-Authentication.rar document.
1. How do I make it so the users are not presented with any options for selecting an authentication provider, I just want people to login with Active Directory?
2. The first step in the Windows-Authentication document (downloaded from link at top of this comment) is to enable the LdapUsers provider. I un-enabled it and it disapeared from the dropdown. Is there any reason why it should be enabled?
3. I still need to remove default from the dropdown.