I worked on your Motion Lab site a bit, hope that's alright. I changed quite a bit in both the css and markup, some things just needed moved around a little. I think it works a little better.
Have a look at it here.
I know, I messed up the left bottom corner... I would just photoshop some color onto the outside edg of that gif, would be easiest that way.
That gap between #wrap and #footer must be from the text in the footer? I didn't mess with anything that far down the page.
At least seems to resize pretty well now.
Validator still shows a few errors to fix.