Just a friendly alert that Microsoft has updated its Camera Codec Pack for Windows Vista and 7, which allows you to preview and open RAW photos in Windows Explorer and any Microsoft application that uses Windows Imaging Codecs (such as Photo Viewer). This newest release includes support for new high-end DSLRs like the Canon 5D Mark III and Nikon D800, as well as cameras from many other manufacturers. Make sure you download the x64 version (labelled AMD64) if you are using Windows 64-bit.
Camera makers have not adopted a universally standard RAW image format, instead opting for proprietary file types that require plug-ins or proprietary software to process the raw image data.