Antivirus and Firewall slowing windows xp speed

I did an experiment. I disconnected my laptop from my local network and disabled norton antivirus and zonealarm's autoloading through msconfig . I had setup my pagefile size to be 20 MBs to 400 MBs. I restarted my laptop and to my excitement, I found my system loaded much faster.. The pagefile size on startup as just 59Mbs rather than usual 150 mbs... I worked on a few applications and after some time, I did give another restart just to make sure if the performance improves a bit futher.

TO my surprise... I find my system to be almost 200% running faster than what it was doing before... Now tell me what should I DO! Should I keep away from norton antivirus autoproject that runs all the time and sucks all my system;s power but protects me by the end of the day... Should I remove zonealarm and open all doors to hackers and trojans and spywares? Can I do just with winxp's personal firewall and keep the zonealarm away? I believe Norton antivirus is one of the best antivirus tools around... But what should I do if it itself is sucking all power of my system leaving it with no power to do anything else?

Life is a mess without these apps, and mess with these apps as well!