What can be added to your home computer to improve its level of security?

Keep Windows Firewall on. Have an anti-virus program running all the time. Don't download anything from the web unless you are sure it can be trusted. You need an Anti Virus Program, and A Spyware program. My favorites are Kaspersky, Avast , NoAdware & Malwarebytes. Avast has a free version, and it works great. Malwarebytes Spyware has a free version also. Keep your virus programs up to date.