I used to use Zone alarm, but I was completely disappointed. full of bugs, crashed my system all the time, didn't release ports, which meant I couldn't restart servers without restarting windows. now I am using sygate pro and I am satisified, it works fine, is user friendly, easy to use. don't know about system resources, I use pentium 3 550 and no problem here, so I don't think system resources is a big problem