How do I tell if an executable is a .NET application?
I prefer not to have to install Visual Studio. But if I have to I will. A commandline program is preferred.
Simpler yet:
Open the properties, look at the tab "Version", if under "Other information" you see a property called "Assembly version" then it is likely a .NET application.
Open the EXE or DLL with notepad or similar app and look for the text "mscorlib" (without the quotes). If you find it, it will most likely be a .NET application.