In a way I want to feel sorry for Valve, but in reality, I don't.
Certainly it was not right for someone to steal the source code for Half-Life 2, and who ever did this should be arrested (however as unlikely as it is).
However, I don't feel sorry. Valve should realize that in a world like today, security is a major issue and many systems are compromised daily. When your connected to such a massive network as the Internet, things like a strong and secure intranet, good firewall protection, regular Windows Updates, and up to date virus-definitions should not be a possiblity, they are a necessity. Valve should of known this, or had a capable IT individual who should of know this, and dealt with the situation after the first few days where issues occured.
I know some may see this as mean, but take an example: If I go to Iraq on a peace keeping mission and get shot in the leg for just being there, it's not really right. BUT I'm still an idiot for putting myself in the situation where I could be shot. It dangerous over there. And so is the Internet.
But I'm not going to bear down on Valve any more than that since I'm sure thier publisher is doing a fine job of that. Guess they can try to look on the bright side: at least thier thier not publicly held.