Second, if you're using Firefox, right click on the image and click View Image Info - this should tell you whether the image is being resized
Third, check for any rogue css. Firebug for Firefox is a great addon for helping with this...
The image is 780 by 82 anyway so no resize going on. I guess a block issue. I am using a image block too.
What was the result of view Image Info in firefox? What does it give for the image size?
The Firefox dimensions were correct.
Another question if I may - how can you make new pages by copying one you have done. I have about 20 identical ones to do!
Any block that I want to repeat on every page (nav, header logo, login, search, etc.) gets added to a global scrapbook.
Then, I edit the defaults of any page types that will contain those blocks and paste from the global scrapbook to the default pages. Once that's done, I use the "setup on child pages" functionality to duplicate the blocks on existing pages.
If you're careful, and you only paste from scrapbook and don't add new versions of the same repeating blocks (nav, logos, etc.) you'll have a minimal amount of cleanup work to do.
I also highly recommend the 'add multiple pages' (http://www.concrete5.org/marketplace/addons/add-multiple-pages/) add-on for fast site building.