gutt,
It's a matter of having the right software and the time to learn how to do it. Pretty much all cameras do a certain amount of processing automatically so pictures look decent straight from the camera, but in tough situations or when you're looking for a particular effect you sometimes end up fighting the camera and the results look terrible.
The real pros take pictures in a "RAW" format which is essentially an unprocessed dataset straight from the image sensor, plus data fields that include such items as exposure, ISO, etc. Once they import it to photoshop or whatever, they manipulate it by adjusting the white balance, colors, brightness/contrast, sharpness, apply anti-noise filtering, filter out artifacts like that annoying purple "fringing" that appears on high-contrast edges in all digital cameras, etc. At the end of the process, they can come up with a unique image that looks completely different than what the camera would have come up by itself using default processing.
The D50 and most (all?) other DSLRs come with a decent set of default processing options and will output a nice looking .jpg file that needs little if any post-processing touchup work. Maybe a little brightness/contrast or extra sharpening, maybe some exposure compensation, but that's about all you'd do to a camera-processed .jpg. But the D50 and other DSLRs also output in RAW in case you want to do all the image processing yourself. The camera *should* come with software that lets you import and process the photos, but in Nikon's case the included software is sufficient but not particularly user friendly. Unsuprisingly, Nikon sells a software package separately from the cameras that is more powerful and supposedly easier to use.
Since Nikon doesn't include the better software with the camera though, many people give nikon software the *finger* and buy photoshop or photoshop elements, or some other software package that can decode Nikon RAW formats. There are even some freeware RAW image packages out there, but you really have to find and try them yourself because each one has custom filters and various features that are all a bit different from the others.
