Used Norton Internet Security for several years. Then I got very bad redirect trojan, which NIS didn't catch or remove. Called Norton for help and they basically said, tough luck we can't help you.
Called Microsoft and they took control of my computer, cleaned it, took a couple hours and never charged a thing. Now they charge for the same service, but still they went above and beyond, Norton that I had paid for did nada.
Then they put me onto free Microsoft Security Essentials, never looked back.