To take full advantage of all of the tools and information the Internet has to offer, you are going to inevitably find yourself stumbling upon some malicious programs, viruses. It is important to protect yourself before engaging in advanced Internet activity. More important than virus protection, is virus immunization. There are several programs that I have come in contact with that claim to protect your computer from viruses, trojans, keyloggers, and various bloatware and only 2 remain as a staple on my system. Those two are "Adaware", and "Spybot: Seek and Destroy".
Spybot has a malware prevention function called an immunization. The program downloads from the site's server the most up to date database of existing viruses, and prevents those viruses from ever entering your computer. Adaware removes all of the irritating web browser clutter that existed because you clicked "O.k." too fast while you weren't paying close enough attention to one of the many pop-up ads you see everyday.
This combination of programs has freed me up tons of available memory, makes my computer run faster, more efficient at not only video but processing levels. It ALSO has an anti-virus feature which I find myself never needing to do with an up to date virus immunization database. It doesn't stay running in the background like most protection programs, eating up all my processing bandwidth.
Over the several years I have spent surfing, streaming, downloading, and pirating every available media able to be put into a computer, these are the only security products I have found worthy of putting on my basic startup program installation disk. Highly recommended.