Two things spring to mind:-

1. A well thought out and logical system of folders on your HD ought to enable you to always be able to find a document again.

2. When filing docs within the folder which need to be kept in date order, prefix the file name/description with the date *reversed* YY/MM/DD. You'll find that any document with today's date (101203) will then always precede any doc with tomorrow's date (101204) and so on. If you use 'forward' dates, they won't.

Hope this helps.