Dungeon Siege disc 2
 

Is there anyone who has finished the game or gotten close enough that can tell me if disc 2 is ever used beyond the initial installation? I have lost, or someone's stolen, my disc 2 and the case and I sure wouldn't want to get a nasty surprise when, after playing the game 36 hours, it tells me to insert disc 2.

You'll be fine. The second disc is not required to finish the game.