Final Fantasy Tactics Advance Official Wallpapers
All of these wallpapers were originally posted on Square's official site. These tend to be pretty high in quality, resolution, and size, so keep that in mind while they're loading. To set one as your desktop background, right click on the image, and select "set as background". If you're looking for fan wallpapers, try the Artists' Junction or the forums. Please note that some of the thumbnails (and wallpapers) may look a bit similar. They all vary somewhat, though. Enjoy!