How to submit malicious software files to Microsoft for analysis

SUMMARY
When you suspect that a file or a program is malicious, you can submit the file to the Microsoft Research and Response team for analysis. Additionally, if you are using Microsoft Forefront Client Security, you can indicate how this program determined that the file is malicious.

This article describes the methods that you can use to submit the file to Microsoft for analysis. The article also describes how to prepare files for submission

INTRODUCTIONThis article describes the methods that you can use to submit malicious software (malware) files to Microsoft for analysis.

More details can be found here
http://support.microsoft.com/?kbid=939288