I'm no expert, just an everyday user. My guru suggested 3 programs for security & to keep my computer running smoothly & I haven't had problems, except with my own typing.
I have good luck using CCleaner every 10 days or so, it cleans up a bunch of junk & cleans up your registry. Before using it the first time, however, go to Options, then Cookies and select the cookies you want to save. Otherwise you will lose passwords that come up when you open a site you have used before. Of course, passwords that you really want to protect, don't put those sites on you "cookies to keep" list. For example, Home Depot's site kept telling me "my store" was 50 miles beyond the closest store until I told it to keep that cookie. Usually takes 2 or 3 minutes to run unless you have a bunch of junk to clear.
Another good freebie is SuperAntiSpyware. Just download and run it.
Just google both of those & they come right up. Both are freebies.
Third thing my guru recommended is just to stay with MS Security Essentials.