When you know the exact version you are running, use that installer to install AC. Simply install as you would any program. When it finishes installing and you first run it (generally it wants you to right click on it and "Run as Administrator" the first time -- although you may not have to), it will ask you where the main database is. Just browse to the server.
It will ask you when you install it, if this will be the main database or not, and you should indicate no.
If you do not have the installer (you should try to always keep the installer and database tuner for every version you install), just post back. One of us will have it. I have most of them.
