Web Database - How to store user information
The one benefit for storing passwords in a separate table, if you have a db that supports this, is you can use a security definer function to read the passwords, and this prevents sql injection or the like from reading it in other queries.  Think of it as being like the /etc/shadow file on Linux.  Of course this is in addition to salted hashes.

This being said I am of the opinion you should really avoid storing passwords in your database.  The less of this sort of thing your app does the less you have to worry about security-wise.  Outsource it to OpenID providers, etc. or if it is an intranet app, something like LDAP, AD, or the like.