This is driving me nuts! I’m an old school graphic artist (meaning print based) that happens to teach design at UCLA. I just put together an iTools homepage for two class projects.

Student Images .

The original images were all created in Adobe Illustrator then copies of the original AI files were exported as jpeg’s. Most were saved with minimal compression and at a pixel size of 360 x 480 @ 72ppi (the self-portrait project.) The monitor resolution was set at 1024 x 768 during the entire process of exporting and preveiwing the files. Here’s the problem - when viewed through through a browser, IE 5, Omni, Mozilla… and the viewing monitor is also set to 1024 x 768, these images look great. However, if viewed on most Windows (and some Mac) monitors at any other resolution, 800 x 600, 1280 x 1024, they look like crap, the anti-aliasing vanishes as if it was never there. How are these files being re-sized, or rather why does the onscreen zoom ratio change. Please school this old fart in what’s going on! My students work deserves better than this. Any thoughts would be much appreciated.

I’m not able to give a full explanation for your problem, but perhaps a couple of thought will help you in searching further.
Firstly, Mac OS assumes a target gamma of 1.8, whereas Windows uses a default gamma of 2.2. Pictures optimized for a Mac without gamma correction therefore display too much contrast and insufficient brightness under Windows. Setting the gamma to a happy medium of 2.0 might help satisfy both platforms.
Secondly (and now I’m talking out of the top of my head, quite honestly), a lower screen resolution means bigger dots, so the geometry of images must change—it would be as if you were zooming in, as you are displaying fewer of your original (or pixels on the screen) in the same area. Does this help explain the apparent reduction in quality?
Your pics, both thumbnail and full-size, look wonderful on a flatscreen iMac, anyway.

Forgot to say that most Windows screens use a different screen resolution, too, so this will also affect on-screen image reproduction. If Im not mistake,the “normal” Windows screen has a resolution of about 95 ppi, whereas Macs are about 72 ppi.