Thumbnail view for RAW in Explorer?

Question

This is probably a stupid question but I simply do not know and cannot find the answer. When browsing files in Windows Explorer, should I be able to see thumbnails of my RAW files?
I have ACR 4.5 installed (and it's in the right location) and can bring up and view files in ACR but it's difficult because when I chose file->open (in the Editor) all I see is the generic unknown icon, so I cannot find a specific images, which is frustrating.

Answer 1

Do this at your own risk, but replacing all instances of NEF by PEF; .nef by .pef and of course, Nikon by Pentax :)
(extract of a post by a Microsoft engineer)
First, an explanation:
For Windows XP SP2, Microsoft made a change in the way thumbnails are retrieved for image files.
Before Windows XP SP2, a Microsoft-supplied default thumbnail extractor was used for any file which identified in the registry as having the perceived type "image".
In Windows XP SP2, this was restricted to images with known file extensions, such as JPG, TIF, TIFF, BMP, etc.
Because NEF files are valid TIFF/EP files, this thumbnail extractor is capable of extracting the thumbnail image, but because Nikon raw files have the extension NEF, the extractor no longer has the opportunity to do so.
Following is a fix for the problem of NEF thumbnails not being visible in Windows XP SP2. But before we get there, a disclaimer:
Microsoft provides this information AS IS AND WITH ALL FAULTS, and disclaims all warranties and conditions, whether express, implied or statutory, including, but not limited to, any (if any) implied warranties, duties or conditions of merchantability, of fitness for a particular purpose, of reliability or availability, of accuracy or completeness of responses, of results, of workmanlike effort, and of lack of negligence all with regard to the information.
Now, the fix:
To restore this component's ability to extract thumbnails from NEF files, there is a simple registry change.
Under this registry key:
HKEY_CLASSES_ROOT\.nef
Create this key (note there are two levels of keys):
HKEY_CLASSES_ROOT\.nef\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}
And set the default (unnamed) value to:
{3F30C968-480A-4C6C-862D-EFC0897BB84B}
Explanation:
{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1} is the string version of the interface ID IID_IExtractImage.
{3F30C968-480A-4C6C-862D-EFC0897BB84B} is the string version of the class ID for the GDI+ thumbnail extractor.