Is this code secure enough

[eluser]achilleusrage[/eluser]
I agree that you should validate the input. Also, you should check this out:

http://www.openwall.com/articles/PHP-Users-Passwords

You may want to store a unique salt for each user in the database (along side the hash). This makes it harder to crack should your user table ever be compromised. Lots of other tips at the link above. Particularly the section on password strecthing.