ATAT's are awesome. But you have to look at what ships are attacking it. A snow speeder was pretty much a scout type ship. It wasnt designed to be used in full scale assults. I'll bet if the Rebs wanted to stand and fight till the end the X-Wings would've kicked their asses.
Lastly ewoks are stupid. I'm glad there are none in TOR.
Seriously though just dig around on wookiepedia.org on anything. Usually there is alotta good answer on their.
can't get behind the ATAT thing. They had a clear and visible design flaw, and the empire obviously has the technology to build an assualt vehicle without friggin' legs. Truth be told, they were made to sell toys of 'em, but that doesn't make them any less silly. I would have loved to see the meeting when they were looking over designs at Empire HQ.
This is our newest assault vehicle, Lord Emperor.... It has the latest weapons and it can WALK!
It looks rather easy to topple, or trip!
No, my lord! Its incapable of being damaged by even the most extreme blaster fire!
What if they...you know, use a rope or something to tie its legs and make it fall over?
Well, then its armor fails and it will explode if you fart at it...but seriously m'lord what are the chances of the rebels even thinking of that?
I'm sold! Start production right away!
As for the mouse droid thing, thanks for the answer. I would have said it could be a Scutter but this was years before Red Dwarf.
Oh, and I know not everything I listed took place in one movie. I was, as I said, mostly joking about. I just didn't feel like listing every movie, though you have a point that I probably should have. Especially since I got III and IV messed up, D'oh!