When choosing security products you need to understand that they should NOT be your first line of defense.
You need to understand the order of importance:
1. User actions- what you download will eventually determine if you get infected. Only download files from trusted sources, if you are not sure then cancel the download and do some research on the source to make sure it is safe.
2. UAC- never approve anything unless you know it is safe, do research on the term that comes up on the UAC prompts before approving.
3. Keep Windows and all of your software updated (especially browsers, browser add-ons and online applications).
4. Choose a light AV that doesn't have issues with your system or programs and has low false positives. (Avast, Avira, AVG, MSE or Windows Defender, Panda Cloud). If you decide you want to buy instead of using free security products, make sure to use a trial version to its full time limit before buying. Many users make the mistake of buying before trying and ending up with a software that doesn't work with their programs or causes issues with their system and maybe be too difficult to understand.
5. If using Windows 8, do not install third-party firewalls and beware of installing AV's, you have been warned, they are known to cause all kinds of problems. For this reason just use Windows default security features along with good downloading habits.
Just remember their is no product proven to protect all users the same way, if you are a careless user you will get infected no matter what security products that you use. Paid products will not protect careless users any better than what free products can. Never think that just because a security product got top honors on testing sites, that they will protect you.
Enjoy!!