Is this 80mb file the one I should include with games?
http://www.microsoft.com/downloads/deta ... laylang=en
Technically yes, but I'd recommend against including the full install file. Just include the web installer; no point in inflating the download size of your game especially in case people already have the latest runtime.
DirectX Runtime Web installer
Develop games in your browser. Powerful, performant & highly capable.
The web installer is ideal for downloaded games, since it's so much smaller. You can also choose the most recent DirectX version - all of the DirectX setups include everything that was in the previous releases, including the August 2008 files.