If you install an original game disc to the hard drive through the Metro dashboard, you will be able to play it with FSD without having the disc in the drive.
You must remember to set a path to your games and the scan depth though (NXE-installed games are placed in the "Content\0000000000000000" directory).
If you ripped your disc using an 0800 drive, you can simply convert the ISO in to a GOD container using a program called ISO2GOD.