Windows 7 Autocomplete question

[babel9]

Hi, I realise this will sound like a very noobie question but I would like to understand what one of the functions of AutoComplete Settings is used for. I am using IE9 and I have worked out that with Browsing History and Favorites enabled these show up underneath the URL bar respectively, but what does the Use windows search for better results function do? I have tried this function enabled and disabled and can see no difference. I assumed that documents and files that are on the hard-drive would show up underneath the URL bar like they do in the Search programs and files field in Start Menu and Search Libraries in Windows Explorer. Example: Type in txt and associated text files appear. I have noticed that Use windows search for better results does not stay enabled if Browsing History and/or Favorites are not enabled. Can someone tell me what this function does?