Password and salt from aspnet_membership table, how to compare to clear text password

I retrieved password and salt from aspnet_membership table.
Their values are
password: 5Zobwg6WUwAEUZXQnmFz0TSJRWU=
salt: aRUPy2Pij0yVGt/zZJ4XGw==
When a user passes a string (clear text password) to a method, I want to hash that clear text with the salt correctly and come up with a hashed password value.  How do I go about doing this?
I have tried a function in this articel: http://thekindofme.wordpress.com/2008/12/04/aspnet-membership-password-hashing-algorithm/
public string EncodePassword(string pass, string saltBase64) 
 { Go to the complete details ...