Dropping back over here to give you an update.
#1.) TURN OFF YOUR FORUM AND YOUR GALLERY BEFORE UPGRADING!
I had turned off the gallery, but I did not turn off the forum before taking the backup. When you restore a backup, it comes back in the way you left it, in my case, ON. Now you've got a few hundred users hammering your site while you are trying to fix it.
#2) MAKE A BACKUP BEFORE UPGRADING!
(Actually, this is #1, but read above.
mysqldump --opt mydata_vbul > bkup102806before.sql
Then, if you have a fowl-up, you can restore your data:
mysql -uroot -mypassword mydata_vbul < bkup102806before.sql
THANK GOD FOR BACKUPS!
Anyway, I am on my way to recovery. For whatever reason, my styles got screwed up, so the answer to that was to REBUILD STYLES in Admin Update Counters.
Then, I ran vbgallery_install.php again and it did in fact run to completion. Apparently, when I ran it the first time, there was an internet hiccup.
It might be good to split the install script up into sections like vBulletin does so as to know where the stuff hit the fan.
Anyway, THANKS for being here. It helps to talk when you're in trouble.