The threats that a PC receive these days are increasing every day with new type of viruses and spywares and Trojans discovered on a day to day basis.
Although there are security threats from all directions, you actually keep your computer clean if you follow some basic rule to protect from such threats. The first and foremost threat for a computer is virus. To avoid virus being instilled into your PC just don’t ever download any file from the computer which you don’t know the source of, as this is the most common way a virus creeps into your PC. The most common route of virus infestation is through email attachments. Never ever download any attachments from someone you don’t know. Download only such attachments which was sent by a known person to you. Even for such downloads, just scan it once through the antivirus and then start using rather than using it without checking for viruses.
Never visit a site which you looks suspicious to you. Just install McAfee’s SiteAdvisor program to your browser which will alert you whenever you visit a site which could be a threat to your PC.
Keep all your antivirus programs updated to the last minute. Use the auto-update option from it to let it update itself without your intervention, this makes it easier for you, so that you don’t have to remember to update it every now and then.
If you could follow these simple measures your PC will be protected from unwanted and threatening viruses for sure.