Just out of interest, is the picture quality any better if the scaling is a square factor?
Say for example, you have a 1600x1200 LCD, and you display an 800x600 screen on it. Surely the pixels would just be quadrupled and you should have a pixellated (obviously) but crisp display?
I've never really used a LCD properly myself but I have seen the blurring that happens when you use non-native resolutions. While they can be very nice in their native resolutions, I'm very happy with my CRT - it deals with everything I throw at it very well.
I am using a 19 inch Sony Multiscan Trinitron G400 with my Amiga 4000 - while it weighs an absolute ton and is huuuuge, it can display the outputs of my Cybervision PPC and scandoubler very well, from those low-res 320x256 games all the way up to 1600x1200. :-D