Whenever I set the header image to height 100% and width 100% (which should make it look normal on all screens
Zencart does not resize this - - it is the size of the native image
I sugest you break this into 3 images
the crest as your logo.xxx file using default code to place the logo and a transparent gif or png
the name as a seperate file image and use the tagline div that exists
The background patern as a tile that repeats in the x parameter
Also a transparent file
Not sure wwhat size a repeating tile will end up but it will be alot smaller than what you currently have
The tile is attached in the css as a background and most likely to the #headerWrapper div ID