I was using NOD32 as an AV until my "licence" expired last week.
I tried Avast because it was free but it let a trojan downloader in, msconfig32.exe that downloaded shed loads of keylogger scripts etc.
Its taken me a week to clear them off and it has really done my head in.
Eventually went back to NOD32 after running almost every free scanner there is in an attempt at clearing them out.
Firewall wise, I'm running ISS Blackice Defender and I have done for years. Not the easiest to live with, but excellent when you get it set up right.
Don't forget Antispyware, I'm running the free M$ one and also A-squared which is also a free one and really excellent.
I have tried several AV in the past Norton, McAfee but problem with these was that they use to make my computer very slow.
Now with growing issue of internet security you need firewall. And I think Zone Alaram with Antivirus is the best salution and that is what I am using at the moment. I had no problem what at all since I am using it. Excellent
i use kaspersky pro 5 on most of my machines for AV and occationally run bitdefender free version as a double check, cos as u can see none of them get everything (Previous posts)
for firewall i use smoothwall v2 (linux box) v3 is out in alpha build http://www.smoothwall.org/ which is running on a old p2 266. if anybody has an old machine collecting dust then its worth it all u need is old machine 2 network cards and the free software from the site. in all honesty u dont have to get near linux if u dont want to, there is a menu system to install once installed there is a web browser interface to tweek and look at logs etc etc. if u decide to have a go with smoothwall there are a few of us here running software and will always help if u need any.
i found za and sygate firewalls ok for a while but they seemed to slow down machine after a while, if u uninstall them and reinstall again they ok for a bit but of course u have to "teach" them whats good/bad again.
Kerio Personal Firewall, AVG Free, Ad-Aware Personal and Spybot. All easy to use, all low on resource usage, and best of all, all free and legal. I've rebuilt about 15 PC's for friends and family this year, and they're what always get loaded on before it even goes on the internet