worms and trojan programs have become more sophisticated lately. SOme are usingremote PC's to attack you with. It's mac address based, so short of swapping out youir router or NIC, reformatting your HD won't get rid of it. Also, for ME based machines, there are viruses that copy themselves to the "auto restore" folder and as soon as you nukle them with your favourite virus program, voila, they reappear. You have to go in and turn ioff aout restore, etc. it's a timely process. Programs like Zone alarm are a level of defense, but any serious hacker will walk through Zone alarm like a hot knife through butter. A good defense is a router, but in many situations, allowing open ports negates all of the security features offered. True enough, you will be fairly secure if you just don't visit any sites, download anything, or enter a chat room. But then you might as well just cancel your internet subscription. Some devices offer high level firewall protection (PIX) these will deter random hackers. But anyone with skills that is determined to get into your PC probably will. The compromise is a router. It deals with the port scanner type of opportuinty attack. I ussually run "netstat" online. That way if I see a connection happening to my network, I can grab the remote IP address and port number. I can also "kill the socket" (terminate the connection from my end). This ussually let's the intruder know that you are aware they are attempting to get in and most of them will move on.