One aspect of firewalls I'd like to hear opinions on is their capacity to filter out advertisements. I know this is not the major function of a firewall, and to many may seem a frivolous concern. But though I own licences for ZAP and Nortons Firewall 2003, I have settled for using Nortons simply because it is far and away the best ad stopper I have seen. I previously used ZAP along with AdSubtract Pro to combine strong firewall with ad filter, but encountered problems: especially that often AdSubtract seemed to slow connections. Nortons does not perform as well as ZAP on tests like grc (and mine even failed the Symantec online test on a couple of points eg pingability); but generally seems reasonably solid, which, along with its great capacity to block ads makes it currently my choice. But I'm always looking for something better, and would welcome comments. My son tested Kerio 4 for a few weeks, and it seems reasonably effective at ad stopping, and reasonably trouble-free on his machine. Oupost seems not so strong at stopping ads. How about Look'n'Stop, or any others?