What huit described is called a "fixed footer" and is a bit different from, and a bit more delicate than, a "sticky footer".
Which one do you want?
A fixed footer remains on-screen ALL the time. It also has a disadvantage: if the users' viewport or browser isn't wide enough, while the rest of the site gets a nice scrollbar to view the content to the right, the scrollbar will not affect the footer. Anything inside a fixed footer who is wider than a user's viewport will be unavailable. If there's not much in the footer that might be ok.
This is what they look like. (dummy page)
Make your browser less wide than 800px. Is that going to be a problem on your site?
A sticky footer CAN be offscreen. Sticky footers stay at the bottom of the viewport when the content is too short to push the footer down by itself. Pretty much exist to prevent web site underwear from showing : )
When content is longer than screen/viewport height, the footer is pushed down like regular footers are. The have no scrolling issues like fixed footers, but they do need some sort of fixed height (you can have a bit of leeway but they can't be too dynamic).
Which do you want? Ryan gave you one way to do sticky footers... I tend to do then another way, but 6 of one, half-dozen of the other...
Both kinds of footers normally use padding on the bottom of whatever container holds the main page content to prevent the footers from covering content. So, as far as I'm concerned, if you're happy with huit's code then adding padding to your content's container (in huit's example it would be #content, in Ryan's (sticky footer) example it would be some child of #wrapperbg, not #wrapperbg itself!) to fix the content-covering problem.
Personally I like sticky footers over fixed because of the scrolling problem mentioned above. However fixed footers have the advantage (if you needed it) of coming pretty much anywhere in source order you need.