Thanks Mike, I'll look in to those things. I appreciae your help and want to make sure you understand my setup so I'm summarizing here:
I went ahead and created 2 App Pools - one for Integrated and one for Classic. Each runs under the same administrative domain account. The entire site directory is granted FULL CONTROL to Eveyone. I am running Windows Server 2008, Sql Server 2008, and IIS 7.
Setting the Site to App Pool Classic, restarting the site in IIS, clearing browser cache, and browising to the site bring me to the standard login.aspx page - with a Windows option/tab behind it. So...no Auto login, but no errors either.
Setting the Site to App Pool Integrated, restarting the site in IIS, clearing browser cache, and browising to the site brings up the 404.0 page and is apparently trying to browse to <site>\Account\Login
I am going to look in to some of your suggestions. Will post my findings next. BTW...would it help if I provided you my web.config? I've noticed a lot of people stating that IIS somehow alters their config file and casues a problem. Just a thought. THANKS!