I have used AVG antivirus and cloud panda antivirus, and iam recently using Kaspersky commercial anti virus, All of which have been quite good products, there are however times, where you need extra security from other viruses, this is where a free online service from VirusTotal comes into reckoning.

1. Create a new message with scan@virustotal.com as the destination address.
2. If you wish to receive the results as plain text, write SCAN in the subject field. If you wish to receive an XML attachment with the results, write SCAN+XML in the subject field.
3. Attach the file to be scanned. Such file must not exceed 20 MB in size. If the attached file is larger, the system will reject it automatically.

Or, Use a small uploader utitlity from http://www.virustotal.com/advanced.html#uploader

Or, Use the browser addons for Firefox or Chrome http://www.virustotal.com/advanced.html#browser-addons

Google now offers a new tool as a piece of javascript which can be added to your site or blog.

The code to add this useful tool can be found at http://translate.google.com/translate_tools?hl=en&layout=1&eotf=1. Blogger users can use the widget below to add this tool to their blog.