Hmm, not sure, but you will have to edit your config.php for the new location.
What about installing moodle1.2 in a /moodle folder, edit config.php, leave data where it is, redirect www.thebarn.za.net to www.thebarn.za.net , delet the old, then unused Moodle 1.1. /moodle
This saves you the trich with the temporary subdomain, you'll get no interruption and you end up with a server wich you can use for something else too since moodle is in a separate folder (also convenient for upgrading 
)
Someone else got an opinion on this ?