I decided to reformat and install TinyXP rev 05 again, and then try different settings on the Intel 815 driver.
The reason is that previsously the Intel IEGD driver trick I found in that thread (see post above) allowed me to use 800x480, but the image was distorted. So I installed PowerStrip to ajust the image (shrink in vertical), but its a commercial product, and before I have to buy it there is a chance it will work by adjusting reg keys that the driver installation reads before first boot.
The problem is that I think that these adjustments are only possible thru reinstallation of OS or driver, because it reads the registry keys after the setup completes before booting.
Will post here the .reg file if I find the correct values.
