What to do with ILSpy error "This file does not contain a managed assembly"?

Question

I'm trying to decompile an unknown Win32 executable using ILSpy. However, it only answers by giving me the useless message: This file does not contain a managed assembly.

I have also tried to use other tools like dotPeek64 and Teleirik without success. Virustotal tell me that it is using:

[+] COMCTL32.dll
[+] ComMgr.dll
[+] KERNEL32.dll
[+] MSVCP90.dll
[+] MSVCR90.dll
[+] OLEAUT32.dll
[+] SHLWAPI.dll
[+] USER32.dll
[+] mfc90.dll

I'm pretty sure it is made with .NET, since this XML is present in the code:

<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
    <security>
      <requestedPrivileges>
        <requestedExecutionLevel level="asInvoker" uiAccess="false"></requestedExecutionLevel>
      </requestedPrivileges>
    </security>
  </trustInfo>
  <dependency>
    <dependentAssembly>
      <assemblyIdentity type="win32" name="Microsoft.VC90.CRT" version="9.0.21022.8" processorArchitecture="x86" publicKeyToken="removed"></assemblyIdentity>
    </dependentAssembly>
  </dependency>
  <dependency>
    <dependentAssembly>
      <assemblyIdentity type="win32" name="Microsoft.VC90.MFC" version="9.0.21022.8" processorArchitecture="x86" publicKeyToken="removed"></assemblyIdentity>
    </dependentAssembly>
  </dependency>
</assembly>

Also note that I'm using Win8 and do not have VS installed. So my questions are:

1. What do I need to do to resolve the above error?
2. What am I missing if anything?
3. How can I check if I have those *.dll's listed?

EDIT: I'm now thinking it was made with plain C++...

Answer 1

This looks like a Win32 executable, .NET executables typically imports _CorExeMain from mscoree.dll. You can use an identification tool like PEiD or Detect It Easy to confirm it.