This panel images are designed to work with a 1440x900 resolution. If you want to use it with another and get the desired behavior, you'll have to modify it yourself.
Trying to change a little bit the l&f of my gnome theme I made this bars from the great theme Slim-Gelatin (http://www.kims-area.com/?q=node/34).
I also wanted to have a fixed size panel, but if you unselect the expand option, ugly border things appear (uggh! puaajj!) and so I made use of the "transparency" attribute of images and gnome-panel (By the way is a very bad transparency. If you put a window under the panel where it's supposed to be transparent IT IS NOT, AND THE WALLPAPER APPEARS SHOWING SOMETHING VERY UGLY!!)
Well, the easy way to avoid ugly panel bordes and used fixed size panel is to set the panel as expanded but use transparent images with the size of your dekstop.
I hope you like it and find it usefull.