If you install the game to your hard drive, you get the full versions of Doom and Doom 2 in your my games section.
Kind of even more convenient than booting them up from the disk if you ask me.
You can play them even without the game in the disc tray.
Frame rate on them kinda seems jacked up though. Classic Doom always this slow?
Edit: Well that appears to be the issue, they realized Doom 1 and 2 run like shit for some reason installed off this disc based version, even though you can still play them like that. No wonder.