What does Peter mean by:

haven't used a firewall ever nor do I plan to. As long as you disable the silly Windows features that open up specific entry points and have a virus scanner (Norton 2003 AV specifically) constantly running and checking emails and files you're about to open then you won't have any problems.

Where are the features to be found?
Does anyone agree with him?

Control Panel->Admin Tools

You should in theory be able to slave M$ networking stuff to a non routeable protocol such as NetBeui.

Ensure you have no internet or admin services running then to all intents and purposes you should be hacker proof.

You still need to test the PC from a remote to ensure that nothing is open, and you don't have any protection against installing a trojan accidentally.

Keeping up with all the security hotfixes is a good idea too :)

Anyone got any suggestions for firewall software on a Macintosh? I run OSX.2

unless you know what your doing, stick with a firewall.
I tend personally not to trust software based firewalls, but thats my choice.
I do not run a firewall, and I can honestly say that I have had very little cause for alarm. I am not plagued with messages saying IP XXXXXXXXX is trying to do something etc so I tend not to worry. Simplistic yes but theres very little anyone could do that I couldnt fix, be it a format and re-install or just simply powering off my CM.

Hacking of someones computer in my oppinion, is not done to the average home user unless you go mouthing off in IRC about script kiddies etc. Theres very little to be had form hacking into a home PC except for pure nuisance causing. However, you could also become infected with a trojan virus, but AV software should take care of that anyway.