The other thing that far too few home users adopt is the principle of least privilege.
It's amazing how much damage you can avoid by taking an extra few minutes whilst setting up your new computer to create a new secondary user account that does not have any Administrative priviledges. Most home users who spend their days browsing the web, sending emails etc. generally hardly ever need all the powers and priviledges that come tagged onto the Administrator account.
The other option, if you can't bring yourself to withdraw administrator power from your fingertips (or you are at the mercy of some incompetent software developer who doesn't know how to write software that can do without admin rights) ..... is to try something like Faronics DeepFreeze
Faronics Deep Freeze Windows Editions - ABSOLUTE System Integrity (I've no association to them and not making any recommendation, you'll need to consider your circumstances)
As Keef inferred too, not all anti-virus is the same, unfortunatley. Even amongst the major players, it can sometimes be surpriseing to see one pick up something and the other doesn't. Particularly in the case of new virus releases. You should ideally look for anti-virus software that contains multiple scanning engines (preferably from well known companies).