Who Owns The Copyright Of Your Web Sites

Hello. This is also on the Tailored.com.au site but I thought I’d add it here because it’s an issue for Web Developers as well.
My thinking with this has always been that the clients pays for the site so we should assign them the copyright of the site we develop. Seems simple enough.
I then had a slight change of mind in an effort to provide better security for our client’s web site and to be better able to grow my business – read my thoughts on that here.
And I’ve just come across this Information Sheet: Websites: Creating and publishing on the Internet (it’s a pdf file).
Copyright ownership of websites is an important issue. Are you comfortable with the ownership of your site?
Regards
Brendon