I've been vigorously attacked on Skype off the level 3 pipeline. This was when I was using XP, and had Comodo Personal Firewall installed. If it hadn't been for my gateway UTM device and Comodo, they would have taken over my machine! Only a Ctrl-Alt-Del and shutdown ended the attack!

I must admit though, that the firmware on my UTM gateway, and the Vista x64 firewall have improved immensely to thwart these kinds of problems. However, I still to this day will not let Skype start with Windows, and only manually start it when I need to.