Getting started with custom tables
 

I'd like to create a custom table for event registrations, and have the table populated by a custom form in vBulletin. Should custom tables be created in my vBulletin Database, or a seperate database?

It's up to you. I would stick to the same database (so vBulletin's database) because it's a lot easier to work that way.

Thanks for the response. I'd prefer to keep it in the vBulletin Database too, I wasn't sure if I'd run into issues when applying vBulletin patches/upgrades.

Nope, you shouldn't face any issues.
In fact, pretty much every single plugin released for vBulletin make adaptations to vBulletin's database instead of creating their own database.

Excellent! I'm off to create a test table and form. I'll probably be back for more help.