Where is DB_Common

Hi, I am trying to install with very little luck the login script from Martin, I have spent days trying to get this to work with no success. I came across some very average instructions today from Luke Williams on how to install it. The instrctions mention needing a package called DB_Common I have searched your site and the net for package with no success. Could you please tell me where I might get this package as I am getting close to giving the whole script / pear the flick as I am getting deeper and deeper into teritory I don't understand. If you know of any better instructions to install this package that also would be a great help. Thanks in advance Paul