.
Alright, just in case anyone's interested ....
Yes, I was able to correct this problem, and no, not by finding the right table or td either.
I have no idea why the table/td section with the logo didn't control the background color in order for me to have no color assigned at all ... which then would have/should have permitted the background outside of the page margins to show through our logo, but here's how I fixed it.

I made a screenshot of the video portal homepage in full screen mode.
Then I took that image and saved a chunk from the top in the exact same height of the table background image ... the one with the planet that should have been transparent. But I left that image in full screenshot width so that I'd be able to view the body background as well.
Then I took our actual body background image, a small gif file (apx. 140 X 140) and compared the left and right sides of the screenshot image to that. Finally I copied a specific matching section of our body background into our table background image.
My theory was that, if I did it correctly, then my new table/td background image would jive so well with the actual body background .... that nobody'd be able to tell the difference between the two.

Last step ... copying the old transparent table/td image into the new table/td background image ... TRANSPARENTLY.

Uploaded the new image, and voila, looks like seamless integration even though it's not.
Take a look for yourself: http://www.meineclipshow.einfachclicken.de/

The table with our logo (the logo is transparent too) resides in a table.
The appropriate table/td contains an image the exact size of that table/td, it's the image with the planet.
To the left of the planet is more of the same image, all the way to the left edge of our page/logo.
And that in turn conforms 100% to the existing body background that you see next to the left and right page margins. Awesome !!!
.