Good question. I would not want to duplicate all my .crw files with .PSD files though.
If you have not tried it already, have a look at Lightroom. It leaves the original .CRW files untouched, but saves what you have done to them in a separate file. I use Lightroom for both my edits and photobrowser, which means that they retain their appearance.
To print or upload to Flickr etc, you just export as .jpg.