I made a Windows Phone App and want to release it to market. However, it only supports Windows OS 7.5. It doesn't support Windows 0S 7.0. So how should I notify users about that? Will App market notify the users when they try to download the app? Thanks!
In the Marketplace you will get an automated notification telling the user that the application is not compatible with their operating system version, so you don't have to worry about this aspect as a developer.
They will not see the Install option.