To get the best from your camera, you should be using the RAW format. However, as camera technology changes, so does the native RAW derivative that your camera manufacturer uses. Each manufacturer use it's own proprietary version of RAW - not very helpful when you consider the long term digital preservation of your precious photo archive.
Most of us also go to reasonable lengths to backup our data safely, but do we consider the file formats themselves? Many people make an uncompressed TIFF version of their processed images, but leave the RAW file in it's proprietary format. Risky. This method relies on software manufacturers always supporting the various versions of each manufacturers RAW format.
For some time, Adobe has been pushing it's DNG format. An open, and fully featured RAW file which is hoping to address the digital preservation issues surrounding the format. The Library of Congress suggest DNG s the only sustainable RAW format - trust me, they know their stuff.
Adobe offer their DNG convertor for free,
here
So, convert your CR2's and NEF's to DNG now - you know it makes sense.