There's an even more encompassing fix, though it involves spending a little money.
What makes thumbnails in Windows is called a "codec", and there's are a couple of commercial packs of codecs available that will make not only thumbnails of raw files, but also of PSDs and many other file types as well.
The two I know about are the FastPictureViewer codec pack (which I use) and the Ardfry codecs. I think there may be another one, though the name escapes me at the moment (Sage something as I recall).
-Noel
