Kaspersky is a good paid product, can be too harsh on not high spec'd machines but the settings can be toned down. It is good however I still clean clients machines from malware as it doesn't really stop everything, granted nothing can.
A good combo for free would be using Microsoft Security Essentials, Malwarebytes Antimalware and Spybot search and destroy.
If you want to pay for a product, go with Kaspersky instead of MSE :)