coldcase: I hope you don't have any problems with the other pc. I am sure you will let us know if you do! Over the last couple of years I have actually removed zonealarm on a couple of under-resourced pcs's (less than 256 MB), as sometimes resources are more important than even a firewall. Once more ram was thrown at them, things were fine. We have it here on 2 pcs's: this one with 1GB ram and the old I8100 with 512 MB. I run it along with AntiVir 7, and Spywareblaster. I have seen more intractable system resource probs with Norton than any one piece of software, other than WinMe and Win98. With their promotions and name many unsuspecting users install Norton with all options turned on, and forever-more their new pc runs like a slug. It's a shame - the early Nortons (system and antivirus) were excellent, and I used them on multiple machines. But that was when Norton himself was the author.
I have heard good things about Microsoft's Onecare Live, but it costs... Maybe it might be a worthwhile way to go for newbies?...Vista will have a two-way firewall, and that will be worth watching too.
There is an interesting firewall guide at http://www.firewallguide.com/index.html