Securing Windows operating systems from Internet assault & increasing predation, is not a single application, or even a suite.
It's layers of protection, user habits, system configuration, real time protection; and most important, threat landscape awareness (because the internet is so fluid and dynamic, it changes almost hourly).
Stand alone suites (CareOne, McAfee, or Norton) give users 'feel good' security, and lull them into complacency, which often has very bad results.
Look through some of the suggested freeware here,
http://www.snapfiles.com/Freeware/security/fwsecuritytools.html
study up, and pick some of the frontline, real-time defenses. Create a restore point after each install, then run the system to verify that application's 'friendliness' with your system before adding other applications.
Make selections based on your skill level & system's other configurations...an application you can't work with is of little use.
Generally speaking: as a system's convenience, interactiveness, flexibility & complexity increase: security decreases.
Core defense applications might include (but not limited to):
Avast! (anti-virus);
Zone Alarm (firewall);
SpywareBlaster (snoopware prevention)
>>>The #1 defense against malware: Firefox, with 'NoScript' add-on.<<<
The key element or common principal is to keep the bad guys (all of them) out of your system in the first place.
Most novice users do not like hearing this, but nonetheless, it's true: using Windows requires you to become a security expert, it's that simple. Something they omit telling you when you buy this system...