MOVIE: Just How Well Known Are The HP Movie Stars?

[Cindy C.]

As an American, I must confess that I haven't ever heard of any of 
the stars of the HP movie (although that Richard fellow rings a 
bell).  On a scale of 1-10, how big are these stars in Britain?  What 
kind of acting are they known for?  And just for fun, what American 
star is the closest analog, e.g is Alan Rickman = Harrison Ford or 
something?

Cindy