If you don't have a virus scan utility installed on your PC, you're asking for trouble. The same applies if your virus definitions are not current. You simply have to update your virus definitions on a regular basis if you're going to surf the web.
The intent of this entry is not to get all preachy about these obvious facts, but to share with you my experience with a anti-virus solution that can be yours for exactly zero dollars and zero cents.
The big boys in anti-virus software these days are Norton and McAfee. Subscribing to either service will cost you some coin and you'll pay annually for the latest virus definitions. It's must have software, so many ante up. I hate having to ante up unless I absolutely have no other options. In this case, there is another option and it's a good one. It's the path I chose and I've since led my mother, My brother and a few friends down the same road. I'm talking about the AVG Free Edition.
AVG licenses anti-virus solutions but makes available a free version for all single home users. This free version includes "AVG Resident Protection, AVG e-mail Scanner, AVG On-Demand Scanner, Basic Scheduled Tests, Free Virus Database Updates, Automatic Update feature, Easy-To-Use Interface, Automatic Healing of infected files and AVG Virus Vault for safe handling of infected files". I've been using it for about eighteen months now and have been very satisfied. The key is you get the real-time protection and full scanning capabilities with virus definitions that are the same definitions created for the licensed version of their software. It's the best deal in town and it works.
If you're without anti-virus software with current virus definitions I urge you to download the AVG Free Edition. It will cost you nothing and you'll sleep better at night. I promise.