For many years I have, at various times, found myself trying to find something in a Notebook file, but am unsure which file it is in. I have to open all the contenders and then try to find it manually. This can take a LOT of time.
As the Notebook file appears to be a proprietary format ( i.e. windows search doesn't know what to do with it) , could you create a SMART*Find tool which I can enter some text and it will search a given folder (and subfolders) for all Notebook files containing the specified text ?