Here's an easy way to make your home Windows PC a little more secure and less susceptible to viruses and malware: Be an average user. If you read any Microsoft Security Bulletin, you'll frequently find the phrase "Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights." I was reminded of this as I read the latest Bulletin from Microsoft. Check out the Executive summary, it's in there : August 10th Security Bulletin.
What does this mean? If you have one user account that everyone at home uses, it's configured with computer administrator privileges. Create a separate account for the computer administrator, and set your other accounts to "Limited" privileges (Depending on your version of Windows, this may be a "Restricted" or "Standard" user type). Use the administrator account when you need to install software or perform some other function requiring the higher privileges. Use your Limited account for normal web browsing, etc. Granted, there will be times when you absolutely must do something with higher privileges - for these you can use the "Run as" option for these situations (right-click on your icon to see the "Run as..." option).
Why would you want to do this? When a hacker creates a malicious script or virus, they will sometimes try to manipulate files that require the administrator privilege. If you're running as an average user and somehow come across one of these malicious attempts to do damage, the script will fail due to the lack of privileges. It's a good step to take on the road to safe computing along with installing a reputable virus & malware scanner.
If you're an average user, run with administrator privileges at your own risk.