robwithamac on "Blog Header Help - Making an Adjustment"

Hello WordPress users:
Thank you for taking the time to help me! I wish to resolve an issue with my blog's header.
Here's what my current header looks like:
http://robertwangsblog.files.wordpress.com/2010/10/screen-shot-2010-10-06-at-3-37-38-pm.png
I have a a custom image that I am using as the header image, but I would like to improve the visual appearance of the header by doing this:
http://robertwangsblog.files.wordpress.com/2010/10/img_0210-1.jpg
How could I go about making the adjustment that I illustrated with the above picture? Any help is greatly appreciated! Thanks!
I think this will make the header take up less vertical room, therefore making more of my content visible as the reader opens the page.
Hope you have a great day.