How to copy an existing (custom themed) site to a new domain

I’m trying to find a way of duplicating an existing WordPress site that uses a custom theme to a new domain.
Once it’s there I’ll do a redesign of the site and redirect the old url to the new one.

Just briefly… I tried following the instructions @ http://codex.wordpress.org/Moving_WordPress
but when it told me to
“3.Go back to your OLD blog and go to options and change the url (both of them) to that of your new site.” It logged me out and caused about 3 hours of trying to get it fixed again !!

So, my question is – how do I copy an existing, custom WP site & theme (including posts etc.) onto a new domain ?

I’m a complete noob at WordPress and would very much appreciate any help given… Thanks !

If it’s a new domain, it’s pretty simple:

1. Install WordPress on the NEW domain
2. Copy wp-content/themes and wp-content/plugin from the OLD domain to the NEW domain (using FTP)
3. Activate the Theme on the NEW domain
4. Activate Plugins on the NEW domain
5. Delete generic content (hello world post, about page, etc.) from the NEW domain
6. Export all content from the OLD domain, via Dashboard -> Tools -> Export
7. Import the just-exported file in the NEW domain, via Dashboard -> Tools -> Import. Important: be sure to check/enable the option to download/install attachments

That should pretty much be it.