it seem as MS has changed things around with win7 and even Vista and support for the DLL was drop because of conflicts with Windows...

 

if you're running 32bit you can try this possible solution (View thumbnails images for PS in WIN)

 

The real solution lays in the proper PSD codecs.  According to Adobe, "This is how Microsoft envisioned extensibility to 3rd party image formats for Vista, with metadata integration with Windows Search and full-size viewing and slideshows in all built-in image viewers, support which was also extended to Media Center in Windows 7... "

You can try a couple 3rd party codec (but they cost...)

FastPictureViewer Codec Pack (which provides good support for layered files saved without the Maximum Compatibility option).

OR

http://www.ardfry.com/psd-codec/

hope this helps
:)
retrocity