You might check into Norton Internet Security 2003. If there is an attempted attack by a trojan, for example, then the IP where it originated is automatically blocked for 30 minutes. During that time you have the choice to move the IP into the "restricted zone", meaning that it will be permanently blocked if you so desire.
I have used this a couple of times and it is a comfort to know that I will not again receive any unwanted gifts from those particular IPs (hopefully).
Incidentally, this software downloads easily from the Symantec website.