Hi all,
I have been using a package called Blackice Defender on my system to prevent any unauthorised intruders accessing my machine.
The package is called BlackIce Defender by a company called NetworkIce.
Address :
Http://www.networkice.com
Unlike Zone Alarm it does cost, but is slightly better in my view.
I also found a package called SamSpade that allows you to hunt down the people who repeatedly hack your system and find out who they are. I used this software to track a hacker who had a go at my machine and sent the information off to the ISP. The replied to the E-Mail and told me that they had dealt with the individual respectively.
SamSpade is free software and lives at
http://www.samspade.org
Hope this helps