[Osiris]

If you need to quickly check a file for malicious code that you downloaded then Virus Total might be something you might want to take a closer look at.This service stands out because it uses multiple antivirus engines instead of just one or two. The antivirus engines list looks pretty impressive because it contains 32 engines.
I was not able to find a engine that I knew of that was not listed, all the major players like Symantec, AVG, Kapersky and Avira are listed which means that the file will get a very special treatment. Even though the file gets scanned by those 32 engines it is no guarantee that it does not contain a virus. No script or software can give you that guarantee but this looks like the best way to scan a file for malicious code and the possibility of success is greater with it.
There does not seem to be a file size limit, at least nothing is mentioned on their pages regarding a file size limit. I suspect that big files will result in an error message after a certain time.
Files can be uploaded using SSL for increased security and it can be checked that the file will not be distributed to the antivirus companies if a virus is found. This is an important option that should be checked most of the time because of privacy issues.
Virus Total offers another way to check files for malicious code. You can send them an email to scan@virustotal.com with SCAN (or SCAN- if you do not want to distribute the sample) and no body text. Attach the file to the email and make sure that it does not exceed 10 Megabytes.
A report will be send after the scan to the email that send the file. Users can also download a shell extension to send files directly from the context menu to Virus Total. Found the link at Make Use Of.