This is the exact kind of situation that made me begin making archival copies of my music ASAP, sometimes before I even listened to it. Someone lifted my book of music cd's from my car the other day, and I just noticed last night.
Lucky for me (how ironic) I made backups of them all, so I can replace them at the cost of burning new ones, however they won't have the great art, and they won't bet the CD's i've spent thousands of dollars collecting.
At least they didn't break my window to get at it, they very professionally disabled my alarm and opened the door took my CD's then put everything back the way it was. I noticed one time when I got into my car that the car last week that the hood was popped, I thought that was strange so I opened it up and took a look, everything looked fine, but everything was not fine. A few days later I noticed that I couldn't find my book of CD's that I keep in my car to replenish my visor CD holder thingy. It had been jacked.
It could have been a lot worse, but it could have been a lot better too. Now I know that nothing in my car is safe, good to know, if I have anything that I don't want thieved either take it with me when I leave my car, or put it in the trunk with all the locks activated.
This thevery coupled with the addition of a smoking area directly outside our door really makes my apartment a LOT less appealing of a place to live.