1. avast
    2)MalwareBytes
  2. A good firewall. Comodo, Online Armor Free or Private Firewall.
  3. MCShield (Will run a very quick scan of HDD on start-up.)
  4. Key Scrambler Premium
  5. OpenDNS

Others…

  1. Super Anti-Spyware Free
  2. Spyware Blaster
  3. CCleaner
  4. Greenshot (For screenshots)

edit: additions