I\'m building a website and my payment methods will be Google Checkout and Paypal. There will be links/buttons which will redirect the user to the secure Google/Paypal sites
You don't need to encrypt the password. You need to hash the password. You really really don't want to have any access to the plaintext password yourself whatsoever, otherwise you lose non-repudiation, which has serious legal consequences. You need to investigate the meaning of this thoroughly before proceeeding.