Password Security

[Tricky]

I'm developing an online system which will need to be secure ... I have created a "users" table using MySql and have developed a login system - For the "Password" column I am wondering what the best (most secure) method of storing this is from the following:

The pages are developed in PHP...

1) Cleartext (yeah right! - thought I chuck it in though!)
2) PHP Function - MD5(string)
3) PHP Function - CRYPT(string, "Encryption String")
4) MySQL Function - PASSWORD()

Which of the above is most secure and why? I have already written a brute force cracker for MD5 (takes a while to run but it cracks it!) so I'm up for discounting that one...