Here are some freeware tools i recommend to protect your self against hackers,and spyware,etc.

AVG FREE -Uses little memory and does its job.

Zone Alarm -Great firewall this is the free version

Hijackthis -Great tool that helps prevent hijackers .Also check out the download section for some more useful apps

Ad-Aware -Good spyware cleaner and tracking cookie remover

Spybot -One of the best spyware scanners

CCleaner -Good registry cleaner

ProceXp -A better version of task manager

Autoruns -Check programs that start up with window

I will update this list as I find more usefull freeware programs.