Случайно натолкнулся на следующую информацию:
Microsoft made their RAW Image Thumbnailer and Viewer PowerToy available for download. This utility provides for viewing of Canon (CRW & CR2) RAW and Nikon (NEF) RAW files as well as TIFF images and other standard image formats (BMP, GIF, PNG, JPEG etc.). The utility is split into a Windows XP shell extension which provides preview / edit / print commands for RAW files as well as a RAW viewer application. It weighs in as a 47 MB download!
http://www.dpreview.com/news/0506/05061501msrawthumb.asp