Windows 7 desactiva el autorun de los USB.
¿Cómo funciona Autorun/AutoPlay en Windows 7?
http://msmvps.com/blogs/dmartin/archive/2009/11/19/191-c-243-mo-funciona-autorun-autoplay-en-windows-7.aspx
AutoRun changes in Windows 7
http://blogs.technet.com/b/srd/archive/2009/04/28/autorun-changes-in-windows-7.aspx
Troubleshoot AutoPlay problems
http://windows.microsoft.com/en-US/windows7/Troubleshoot-AutoPlay-problems
AutoPlay: frequently asked questions
http://windows.microsoft.com/en-us/windows7/AutoPlay-frequently-asked-questions
How to Enable or Disable Autorun for Removable Media in Windows 7
http://www.sevenforums.com/tutorials/27544-autoplay-enable-disable-autorun.html