Dual Monitor setup in 9.10 - Desktop background doesn't extend all the way

[dsiukola]

I'm trying to get the extended desktop working for Ubuntu 9.10. I have a Dell Optiplex GX620 with an ATI x600 graphics card. I have two 17" monitors, each with a 1280x1024 resolution. I can physically use all of my real estate, but I don't really know how to describe the fact that my desktop background doesn't cover my whole 2nd monitor.

My panels extend correctly, and I can place windows over the far right side. However the desktop background just takes the image of the window that was over it, not the desktop background. I've attached an image showing my problem. Any help will be much appreciated. Thanks.

[bigsmitty64]

What size is your wallpaper? I seem to remember having to have a wallpaper that is double the width, like 2560x1024 and have it set to "tile"

[dsiukola]

My desktop background from the screenshot was just under the Solid colors option from Appearance. If you choose that, there's no option to Tile, Zoom, etc. I also have a 2560x1024 desktop background set to tile, and the image is just truncated at the point where the desktop looks weird.