Didn't you have some grief earlier in the year with people having a go at your door, or am I getting confused with someone else?
Sorry to hear that your pride and joy has been attacked mate, its truly gutting when it happens - I know from personal experience, as I've had several of my cars done in the past, ranging from nothing gone (but plenty of damage) to a full-on Alpine install go.
All I can suggest is to spend any and all available money on security rather than other mods, until you're satisfied that your car is suitably protected from the opportunist thief, and until then don't leave anything in the car - I've had a window smashed before so some kids could nick probably no more than a tenners worth of change from the ash tray, so a radar detector and stereo are going to seem like a kings ransom compared to that!
Get it belled up as soon as possible!