Upgraded to MediaWiki-1.4.4 - the current stable release.
I remembered to move the custom wiki.png from the old stylesheets/images directory to the new skins/common/images directory.
Also, I remembered to to chmod a+w images to allow access to a temporary directory.
Finally, I copied the value of $wgSpamRegex from /includes/DefaultSettings.php to the new file.
Upgraded to MediaWiki-1.3.7 - the current release.
I remembered to move the custom wiki.png from the old /stylesheets/images directory to the new installation directory.
In addition, I have to chmod a+w images to allow access to a temporary directory.
Upgraded to MediaWiki-1.3.5 - the current release.
This time I remembered to move the custom wiki.png.
Upgraded to MediaWiki-1.3.0 - the current release.
I turned off the Global_registers settings. Let's see if anything breaks.
I had to make the images directory writable again. This is due to running in Safe Mode.
I got MediaWiki-1.3beta5 to install.
I had to increase the PHP memory limit to 20M and make the images directory writable.
It's a very good site !! Very nice work, admin :) Good luck !