Not a fan of the free a/v products, outside of MS Essentials/Defender as they tend to advertise the pro editions too heavily for my taste, doubly so with AVG.
I haven't changed the below combination of programs since I first got Windows 7 installed in May 2010, though I have a lot of experience getting machines up to scratch so it might be a little difficult for some to setup themselves. The below I have installed on many other computers and it is rare that I ever see them again with another virus, trojan or other unwelcome web code.
MS Essentials for antivirus. Yes this program is active scanning if enabled.
On slow computers though, I make exceptions for its folders and svchost.exe (windows update).
Spybot search and destroy for malware, spyware and immunization feature to stop some nasty stuff getting in to begin with, or calling home afterwards.
MalwareBytes Antimalware for malware, I have the pro edition for active scanning.
Note that MBAM scans for different things than MSE so they work fine with each other active, as opposed to Norton and AVG which I had 'fun' untangling when someone managed to get both installed on their computer.
To give the machine a basic clean, I use Piriform's CCleaner and Defraggler, note not to use Defraggler if your machine has SSDs (Solid State Drives).
For deep infection removal, I use AdwCleaner first and in major cases Combofix (do NOT run this unless you are told to) when something really nasty gets into a computer that all the above can not remove.
Other tips I have are to use Adblock Plus and https everywhere. Hit up Google to find them.
Be careful which sites you visit and not click randomly on email attachments.
Not related to computer security, but Lazarus Form Recovery can take great frustration out of using forums.
Ever lost a post because you hit refresh instead of submit? Grab that and thank me later.