Belagarath - Sean Connery. yes. Only him.
Polgara - Sigourney Weaver. Never thought of that... maybe. I still like Terri Farrell for that.
Garion - Shia LaBeouf, maybe for the younger one. I'll say Sam Worthington and Ryan Reynolds
Cenedra - Kirsten Dunst? (oh dear god no), Felicia Day maybe, she knows the material at least, and is a redhead. Maybe Alyson Hannigan
Durnik - Hugh Jackman
Silk - Brad Pitt, Matt Damon, Liev Schrieber, David Tennant, Ryan Reynolds
Barak - James Gandolfini, Brian Blessed
Mandorallen - Liev Schrieber, Hugh Jackman
Hettar - Only because of lord of the rings, Karl Urban, maybe Christian Bale
Lelldorin - A while ago I would have said Heath Ledger, but now I don't know.
Belgarath. I've always said Connery. That isn't going to change.
Polgara. Sigourney's too old. I'm sticking with Teri Farrell.
Garion. Husband, if you let Shia Leboofhead *near* my movie there'll be trouble. Young Heath Ledger, around the time he was in whatever dreadful Aussie soap he was in, might have come close. Actually that kid in Supernatural - the younger one - might make a decent Garion, as well.
Ce'Nedra. Kirsten Dunst, I think not, baby puppy. Aly Hannigan's not quite right. Felicia Day might pull it off if she wasn't so tall. Still looking for my Ce'Nedra.
Durnik. Jury's still out. Gabriel Byrne might've pulled it off as a much younger man. Nobody really appropriate springs to mind just now though.
Silk. Has to be Tim Roth. As non negotiable as Connery...

Barak. I always said Brian Blessed would have to play Barak. (CHISWICK! FRESH HORSE!!!)
Mandorallen. Yanno, Liev Schreiber might almost pull it off. But I'm gonna go with... Alan Tudyk

Stick him in armour and pad it out a bit, he's already got the guns ;-)
Hettar. JET-A RI!!!! WE RUV JET-A RI!!!!
Lelldorin. Hmm. How about Chris Pine.
Eriond. The kid in the Cadbury ad
