Although Vin Deisel has the bald part down, I just can't picture him as Minsc, too much "edge" IMHO.
So perhaps Michael Chiklis (sp) as Minsc.
Kate Hudson would be a good Aerie, or maybe Shannon Elizabeth with her hair dyed blonde.
Nalia's portrait reminds me a little of Drew Barrymore. So that would be my choice there.
Perhaps Charlize Theron as Jaheira, she would have the looks and the hard edge of her character.
Ving Rhames as Valygar.
Well that's a start.