Where are you trying to view these images - web browser, slideshow, Photoshop, etc.?

I am also wondering what you mean by the switched resolution to 72 pixels - that should be itty bitty teeny little block on your screen - unless of course you're talking about dpi - and then it doesn't matter at ALL what the dpi is set to when viewing on your computer. It's still 1280x960 pixels whether it's 10dpi or 600dpi. DPI only means something when you go to print an image - until then it doesn't mean anything.

You could try upping the res of your MONITOR to larger res than the image.
-Lew