Just recently been suggested by my colleague to use these software for antivirus, firewall and spyware protection. It’s all free and lightweight

Avast Anti Virus – http://www.avast.com/en-au/index
Comodo Firewall – http://personalfirewall.comodo.com/free-download.html
Malware Bytes – http://www.malwarebytes.org/products/malwarebytes_free