I just heard the soundtrack for movie four.  It was excellent!  Hogwart's Hymn was incredible and is my favorite.  The Quidditch World Cup is also very good.  I can definitely say that I will own the CD for GoF just like I own PoA.

Additionally, I just put down $5 to pre-order Goblet of Fire for the PS2.  The only other HP game that I don't have, coincidently, is the Quidditch World Cup.  The Harry Potter games may not be the most challenging, or even the best looking; but there is something about them that I really enjoy.  I just love getting lost in the universe...stomping around the grounds, going to classes, searching the halls - it's just fun!