When you buy a compact digital camera, you buy a camera. But when you buy a digital SLR, you buy into a whole camera system. That SLR body accepts a wide range of lenses, flash units, viewfinder attachments, optional power sources and other accessories, all of which add tremendous versatility. So to get the most out of your purchase, you should look at the whole system, not just a particular camera model, when deciding which D-SLR to purchase.