I love header using landscape. I tried to make one using gimp. If you don't have photoshop the closer program that i can recommend is gimp...you can also use the brushes made from photoshop which it is so handy.
You can read my post about vector graphic, image manipulation tools and Gimp is that i recommend -- during that time i have not much knowledge of how powerful gimp until i decided to give a try read a lot of tutorials and i love it so much. Photoshop is so expensive and gimp is free so which one is great for practice? of course the free one until you are skilled enough and not satisfied then that is the time you use photoshop but at the moment i can't see the reason not to enjoy gimp instead.
Below is the sample of how great gimp is...if you notice the background image of my post title it is one of example of how great gimp is...here's my other sample.
Please let me know of what you think.
Here are tutorials to help you started with gimp:
I hope you like what you read and let me know if you want to use the image for your header and i will give you some link including psd to learn how i did it.
original image jpg