Just set AIM to only allow people on your buddy list. I don't know how people can ever get anything done if they have those damned windows opening all the time...
I also only have coworkers on my buddy list. That way, if they start AIMing me, I can drive the less-than-one-mile to NASA, get through the security gate with my contractor's badge, and personally beat the living s*** out of them. Then I can get shot by a security guard.