Good free antivirus and firewall programs

I've been using Norton for the past 3 years, but not only is that thing expensive but it's also a titanic system hog. So, are there any free (Or cheap) antivirus and firewall programs that are comparable to Norton and Mcafee's offerings?

Zonealarm.


Or lunix lol.

Avast! and Clamwin for the antivirus.
Windows Firewall as the software firewall. Or Zonealarm if you enjoy being alerted of perfectly legit traffic all the fucking time.
Microsoft Antispyware and Spybot (without its resident) as anti-spyware.
None of them costs money.

And lunix of course lol.

Grisoft antivirus, ZoneAlarm firewall, and Spybot Ad Aware

I recommend Sygate if you can still find the free personal version.

Grisoft's AVG.