Ah, the possibilities of hero/anti-hero here are endless!!!!
 
Billy Connolly and Gerard Butler-both should share the hero/ferret
enabler roll.  The villain?  I think John Cleese would do well, or
Eric Idle.
 
OR how about Robin Williams and Billy Crystal?  James Woods as the
villain.
 
Oooooh, wait.  I've just had a telepathic message from the crew.  The
perfect villain, at least the person who could play it with humor,
etc.----Glen Close!
 
I think all of the above would be great, and besides, Connolly and
Butler are Scots with a great sense of humor.  And If Connolly can be
a herptologist (I hope that's the correct spelling) in "Lemony Snickets"
I know he could be fantastic with ferrets.
 
Rebecca & the Crew of Merry Mayhem
 
"Do not meddle in the affairs of dragons, for thou art crunchy and taste
 good with ketchup"
"Support bacteria, it's the only culture some people have"
[Posted in FML issue 5337]