Do you find that when you install your application you get one of these…

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If so, then you need one of these.

The Program Compatibility Assistant is designed to assist users with applications that were not designed for Windows 7. It monitors applications and installers and, if they do anything that could be considered as incompatible, throws up the above dialog.  Now sometimes PCA gets it wrong when nothing untoward has happened, therefore confusing the user. If you want to switch off PCA for your application then you need to add a Windows 7 manifest.