Malwarebytes Realtime Protection Well Worth the OTLF
I know and appreciate your emphasis is on the " free tools" and, without question Malwarebytes is among the best. It plays well with most any Anti-virus or Security Suite (paid or free), that is out there. However, IMHO, the paid version is essential, as, it will proactively prevent the Malware attack rather than retroactively removing an infection that may well have caused harm far beyond the PC's operation (e.g. data loss,password or identity theft, etc.).
When properly configured for both real time protection and routine automated definitions updates and automated scans, Malwarebytes will likely save far more in $, time, support expense that often results from a successful attack, than it will if used only with hindsight. For these reasons (and respectfully to Jack) paying the modest one-time license fee for Malwarebytes is the best free advice I can offer to anyone interested in their systems security.
On the Free side of AV software to compliment Malwarebytes, I echo earlier favorable comments on Microsoft Security Essentials for Pre-Windows 8 machines. As I understand it Windows 8 will "essentially" have a renamed equivalent built in.
DISCLOSURE : I provide in home and remote PC tech support and though it may be counter-intuitive for my business, my personal experience with Malwarebytes makes it the one program I routinely encourage my customers to purchase. Other than the CrossLoop products, it is the one paid product license I choose to "sell" at my CrossLoop profile.
