Spybot S&D is older, now obsolete software. While it still does offer protection, the alternative, Malwarebytes, is better. Even with the free version, up to 10 updates per day come in. Malwarebytes also offers a lifetime license, pay once, and also you get resident real-time protection. Free version works just as well, but no real-time protection is included.
Avira, AVG, Avast!, to name a few, all offer good protection at no cost. While MSE is good, it is not rated as high as the three noted.
Which free security tools are the best? I know it's probably a matter of personal choice, but a worker at the local computer store said that Microsoft Security Essentials was no good, and recommended using Avira and spybot s&d. Is he right?