2013 preview file association issue, none of my office files are recog

Hello, I have installed 2013 preview and all has gone well. However, there is a file association issue because none of my office files are recognised.

From within any of the 2013 applications I can open my files, no problem, but opening from outside word for example clicking on a word file on my desktop brings up the which program window. Attempting to create the association through the default programs dialogue does not offer the possibility to associate with 2013 applications as they are not listed.

Your help and guidance is very much appreciated.

Peter