Adobe has been dragging their feet for more than 18 months on this one – they can’t seem to ship a working DNG Windows Imaging Component compatible codec for a 64 bit based Windows system. Along comes the FastPictureViewer WIC RAW Codec Pack – which fully supports DNG on 64 bit Win7 machine. From my initial testing and reading other reviews, it makes DNGs (and other RAW file formats that would require other codecs) just work.
It also works on Windows 32 and 64-bit Vista and Windows 7 (and XP SP3).
It’s donationware (meaning you should donate to the author if you want to continue to use it after a trial period).
I use DNGs exclusively – and was frustrated by the lack of explorer thumbnails when browsing folders (as was my wife when she’s looking through our photo folders stored on our Windows Home Server).