Success: Xenarc, Epia MII, and aspect ratio under Linux
Many of us are trying to find a way to get the native screen resolution of our Xenarc monitors (800x480). This screen resolution has an aspect ration of 1.67. It turns out that 1280x768 also has this aspect ratio and looks very good on the Xenarc. I am using Linux, but Windows users may be able to find this screen resolution with their driver as well (I haven't looked).
I am running Gentoo Linux using the viafb framebuffer driver. I have added options to my grub bootloader telling it to load the viafb driver and set the screen resolution to 1280x768 @60Hz. This works perfectly.