This setting controls whether the automatic text completion (AutoComplete) feature of Windows Explorer appends the suggested text to the words as you are typing as well as showing a drop-down list of available values.

To change to Auto Complete mode, follow the next steps:

1. Open your registry Start -> Run, type regedit and click OK.
    
2. Expand HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\AutoComplete (see picture 1).
   
   

   Picture 1

3. Create a new STRING value, or modify the existing value, named "Append Completion" and set it to "yes" to append the suggested text as you are typing or "no" to only show a drop-down list.
    
4. Exit your registry. The modifications you made will be in effect after you restart or logout you PC.

Note: This setting also changes the auto complete functionality of Internet Explorer.