[Javascript] Re-assign URL of swapped image

[Thierry Lavall=?ISO-8859-1?B?6Q==?=e]

Hi,
Please see
http://www.8p-design.com/Bummis/New/en/Products/covers/BummiCotton.html

When you click on the two swatches, the diaper image swap. All fine.
Now, I would like the user to click on the swapped image and get directed to
a LARGER copy of the image in another window. But, I don't know how to swap
the URL when changing the image.

Could someone guide?

Also, if someone has a better/cleaner javascript than the one I'm using for
this image swap, please point it to me. This one works, but seems bulky for
nothing.

Thanks!
-- 
Thierry