Perhaps something like this?
I'm not quite sure how this will render on a Mac...
IE5 and Netscape 4 seem to handle it okay.
I set the horizontal size at 400 pixels to tile it twice at 800*600.
I worked on the base jpeg, which you are familiar with, in Adobe PhotoDeluxe (PhotoShop's poor cousin).
I set the contrast to "not much" and the brightness to "whole bunch" and saved it. It should also be saved with less detail to shorten download times in the real world; but that's for later.
...details as you'd like,