Website Banner / Header Designs Required (Graphics)

Hi guys.

I have a website (http://www.aerialinstallers.org)
The website consists of 11 service pages.

The pages are:-
Home Page
Aerial Installation
Aerial Repairs
Freeview
Radio Aerials
Communal TV Systems
Sky Digital
Freesat
European Satellite
TV Wall Mounting
Contact Us

These pages can be found on my site using the navigation bar.

Currently I already have a banner, but this banner is replicated across the site.
I'm looking to have this banner redesigned as part of the process.
The banner size has to be 960px wide and 250px high.

This project I have given out before, but it has proven to be a difficult task for many.

Before I commit to any proposal offer, I will need to see evidence of previous work, ideally banners and also a concept design for me to see, just to make sure we are on the right tracks.

I cant really give any ideas of what I want, as I want the proposer to have the creativity and experience of what should be needed for a great looking design.

I have attached some links to sites that I do like the look of.

Look forward to your feedback.

Chris.