I've seen many complaints of the Gadget Gallery.
I thougt that it would need a redesign but I couldn't imagine how it could be better.
But I've seen the solution in the new mobile phones:
They have a thin sidebar (that you can show or hide quickly) with all your gadgets, and you can drag & drop the one you need to the desktop.
I think it would be easier and faster to use them. For example you could show the gallery without a click, only moving the cursor near the right side (when you have the desktop in the foreground).
MS removed the old sidebar, but maybe it only needed to be rethought.
Redesign the gallery with a sidebar shape.