Good PC Protection (Anti Virus etc.)

I'm looking for some PC protection (Anti virus, Malware, Rootkit all that good stuff)

It has to

  • Be Free
  • Not ask me to buy it every 5 minutes
  • Actully do Shit

What would you recomend? All I currently use in terms of PC protection is Flashblocker and adblocker, (I have it disabled on Teksyndicate :D) Security Essentials, and Malwarebytes. 

Also how often should I be scanning with these. The less frequently the better yet still giving my good protection (I use an SDD so I don't want to whear it out quickly)

Iv'e found that spybot search and destroy have done me some good. You just need to make sure to update it.