X-Ray is a free utility that allows you to submit suspicious files to more than 30 antivirus laboratories for analysis, or for an immediate security scan using VirusTotal. It updates automatically and is portable, making it the idea tool for people who are serious about security.
Submission of samples is important so that security professionals are kept up to date about new virus threats. X-Ray does this via web forms or email. In some cases, you'll need to do a Captcha, to make sure no malicious reporting is going on.
As for scanning, X-Ray works by sending the file to VirusTotal, so it can be scanned by multiple scanners online. There, it's tested by up to 31 different antiviruses. The results are shown in a table, and any positives are marked in red. X-Ray also offers a history function.
Keep malicious programs at bay by using X-Ray. You'll be helping the whole internet community.