Irfanview works great. The Print Screen button is "supposed" to take a screen shot of what you are doing and save it in the Screenshot folder within Neverwinter Nights folder. The only problem is the Print Screen button doesn't always take the picture - it will fail from time to time. Your best indicator that it worked is when you see a momentary freeze in some animation on your screen after pressing the button. It doesn't work 100% of the time, so take multiple screen shots and then sort them by date in your Screenshot folder. The files will be saved with a .tga (Targa) format. Use Irfanview to convert them, crop them, etc. in JPEG format.
I speak from experience on this one. DMs screenshot everything.
Sultan