Quick post today. Some of you may have run into this issue previously and while I figured this out myself this morning there also appears to be a technet article here talking through it in more detail.
In summary, if you have an issues with the VS 2008 Redist now showing as an install pre-req when trying to install the Authoring Tool, it’s most likely because the Redist actually didn’t install, as it doesn’t always install just by running the package as you’d expect.
To resolve this, browse to the C:\VS 2008 Shell Redist\Isolated Mode folder that the AppEnvRedist.exe created and run the vs_shell_isolated.enu.exe directly.
After the installation completes attempt the Authoring Tool install again and you should be good to go.