I highly recommend you to use Kaspersky Internet Security 2010... The program is light on resources and is VERY powerful.. I've been using Kaspersky since like 2006 and haven't had any spywares/malwares/viruses... etc on any of our computers at home (We have 7)... Check them out: http://www.kaspersky.com You can also download 30-day free trial!

I recommended this to many people and they are all happy.. so I hope I have helped you out here too..