If it is installed and you didn't save the installation files when you first installed it, there's no way to create an installation file from your system.
I'm not sure, but the version is 14 something and 2011 is 15 something, so this may be what you want. Be warned that I've heard uninstalling 2011 is a bear and sometimes prevents installing 2009 even when uninstalled. I'd use Revo on 2011 or Windows Live Essentials - Uninstall
to be more sure. Again, I don't know for sure if this is it, but it's all I could find other than torrent sites after 30 minutes of searching. Download Free Windows Live Essentials, Windows Live Essentials 14.0.8064.0206 Download
. I also understand you can't mix and match programs from the different versions, so if you switch to 2009, you need to switch all the applications you're using and not just Windows Live Mail (though you can choose to install and use only WLM 2009).
I hope this helps and is what you're looking for. Save this download and you should be able to use it to install on another computer. I'm almost positive it works with Windows 7. You will need to separately save your data and settings from your current version if you want to transfer them to the new/old version.