For nVidia cards, the display can be set up for various scaling methods (for when using a res lower than the display's native res):
- Use NVIDIA scaling
- Use NVIDIA scaling with fixed aspect ratio
- Use my displays built in scaling
- Do not scale
I'm not sure about ATI, but there should be a setting somewhere in the catalyst for it.
Personally I would buy the 1920 over the 1650 - you get more screen space for everything when you're not rulling full screen games, and scaling doesn't look too bad - I played both crysis titles on my old 8600GT running at 1024x768 on dual 1920x1080 monitors (the game on only one of them) and it was fine (since I got a GTS250 my gaming has owned at full res for everything). Text isn't as crisp as running at native res, but apart from that there's not much to worry about...if you run games at 1650 on a1920 screen there won't be a huge amount of scaling anyway.