Check your local state laws. In most places if the car is over 10 years old, odometer rollback isn't classified as fraud for a vehicle that old.
Given it was purchased on Aug 13th 2003 you have about 3 weeks to see if you can take any action.
What I don't understand is why you did the Carfax AFTER you bought the car? Whats the point really?
Plus since you paid $5K for it, you paid roughtly what an 200K miles E46 is worth. If you paid $10-15 for a 63K mile E46 then its a whole different story.