I found an old (Access 2000) KB article on security which was interesting reading:
http://support.microsoft.com/default.aspx?scid=kb;en-us;165009

Also interesting is that user level security has been dropped in Access 2007, though it will continue to support Access 2003 MDBs withe user level security. I assume that this is because having all the security contexts on the computer make it too easy to crack.

The only real user security which is not filesystem related that I can see in Access 2007 is securing the (entire) MDB file with a single fixed password which is used to encrypt the data.

So I don't think that hooking into Windows Authentication is going to help - other than providing a login to the application, which is really just window dressing.