I need to make a correction there, Bongman.
You don't need strong fingers or finger dexterity to play the piano. What you need is a well coordinated movement of the body and finger. This applies to playing fast in the piano.
Let me share you my experience.
I used to practise hanon and czerny for long hours ( 4 to 5 hours) everyday. As a result i developed Carpal Tunnel Syndrome . I felt painful everytime i play the piano. I spent lots of money going to physicians trying to cure my fingers. After few months and several hunderds dollar(could be higher i dont know) poorer. Then I can play properly again. What a waste of time and money.
I was desperate. I thought that these concerts pianist must have superhuman finger strength and dexterity. After done some research on the internet, I discovered that the key to achieve speed and playing well is by knowing the right movement and coordination for the fingers.
What happens when you play hanon or other finger exercises is that you stumbled upon the right movement when you speed up. But this will take a lot of time. Instead we can use of the time practising other things more musically like learning songs instead of practising mindlessly on Hanon, or at least learn more etudes to practise your technique.
Here's some book recommendations for practising your posture and finger movements, I have a copy of these books as well:
Mastering piano technique by Seymour Fink, Includes DVD too
http://www.amazon.com/Mastering-Piano-Technique-Students-Performers/dp/0931340462
Gyorgy Sandors on Piano Playing
Piano Power by Richard Prokop
Freeing the Caged Bird DVD
http://www.freeingthecagedbird.com/
I have other books too but these are the BEST resources for practising finger technique in my opinion.
This sites also helps in teaching you to practise properly
http://www.pianofundamentals.com/
or check out the site that me and my friends have developed as well here if you want to learn pop piano technique
http://www.poppiano.com.sg/