Find installed MSVC with NSIS Installer?

I would like to find out if any kind of a Microsoft Visual package is installed during my Nsis installation (I need the Compiler from those Microsoft packages (C,C++ Compiler))

One possibility could be to have a look in the registry...but it would always be a different entry.

So far I´ve got no good solution to detect a MSVC maybe anyone else does?

Your best bet is probably to look in the registry. You could take a look at some open source build tools and see how they do it. (SCons etc.)

The other alternative would be to search all drives for cl.exe with FindFirst and friends but that could be slow and you would probably have to check the version information to filter out false positives...