I just pushed the changes to windows-3rd-party and fgmeta to use OpenAL-soft on Windows, and hence drop the need to run ‘oalinst.exe’ as part of our Windows installer. This will also fix the issue with the (pre-built binary) Creative Labs OpenAL being stuck on using the VS2010 runtime and hence us reporting a missing msvcp100.dll on systems where that redistributable is not present.
I tested on my Windows box and sounds seems fine - there were no source changes to Simgear or Flightgear since OpenAL-soft is a drop-in replacement.
If you run nightly builds on Windows, please do an uninstall of OpenAL (assuming nothing else on your computer uses it!) from the Windows control panel, and then test an installer from tomorrow onwards - it shouldn't ask about OpenAL installation, but sound should work (and sound!) exactly as before.