Check programmatically for installed runtimes (.NET / J# / C++)

Hi,

I'm writing a trouble shooting utility that checks my assembly
references. It creates a report for the support.
Now I want to add some routines to check for installed runtimes.

Ok, the .NET runtime is quite easy to retrieve: Checking the registry
key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework for the
installed/required version.

But what about J# and C++ runtime? How check I check if they are
installed correctly? Is there also a registry key available? Or do I
have to check for some files in the windows / windows\system32
directory?

Thanks a lot for your help in advance!

Best regards,
Ralf