lucy24 - 6:51 am on Mar 9, 2012 (gmt 0)
I have plenty of content and the footer still appears about 20px below the header.
Uh-oh, that sounds as if it's simply being planted in the wrong place. Or it's overconstrained. Something coming through as absolute that should be relative, that kind of thing. Does it cover the page content, or does it interrupt it? Apart from being in the wrong place, does it otherwise look as intended? ("Apart from that, Mrs Lincoln...")
Better post the footer css. And the relevant part of the html that calls it.
I hesitate to say this because people tend to dump their entire style sheet, on the off chance that there's some connection between the header color in the navigation links and the footer placement at the opposite end of the page. Or something like that ;)