Simulating Frames with CSS - Help!

I am trying to do a quick mock-up for my mother-in-law and i need the logo and navigation area (header) to stay the same thru all the links, while the content of each link changes. Can I do this with CSS? I refuse to use frames and she wants an HTML and a Flash site… I can deal with the Flash, but this is a problem.
Any help would be much appreciated!