I've cleaned up and re-released my pumpkin theme, and at a new home. Now with validation! :)
It is 3-column format, very boxy with lots of orange. Fixed sidebars, fluid center. The stylesheet and template files are pretty straightforward, and the stylesheet is well-commented so you should be able to easily find the spot to change the header pic.
I've also enclosed a second header pic in case you wanted frost on your pumpkins. It can all be found here.