I can say little that hasn't already been said about RAW but, I call it a "lossless" format in that it's like a 35mm negative that you always have regardless of how much it's been printed, color corrected, etc. I use to shoot just jpegs till I saw how terrible the final product was for printing after I did a bit of post processing. The image was not only less sharp but displayed artifacts and for me destroyed the reason for shooting jpegs...more shots per card.
When I got my Nikon D200 some years back I started using their Capture NX2 exclusively and never looked back. I'd make my changes in the RAW file, crop, color correct if necessary, sharpen, remove sticks or whatever from the background, etc. and then when I was happy with it would "Save As" a jpeg file which was usually between 1.5-5mb size rather than the 15.5mb RAW file, which I still had unmolested. With a 4Gig card I can still get 240 RAW images from this camera...more than I'd ever need.
