In the homepage field of the comments Drupal tries to force the user to put in http:// in from of the site. I wans users to be able to enter in the following and them all work

http://domain.com
domain.com
www.domain.com

Someone posted a way for the field to auto populate the http:// here http://drupal.org/node/14718 but I want it to work in a more user friendly way. I want Drupal to add the http:// if it doesn't exist.

Can that error checking be overided in the theme files or is this something that will need an actual module written to create a whole new error checking function?

to be honest, the error checking for that field is no where close to adequate anyway. I can give it http://domain/ without any extension and it works.