Iain:
due to warez (illegal users) of vbulletin this site has restrictions in place, to answer your question. without the info no we can not answer any questions and you can not download hacks or get suport, the same applys to vbulletin.com.
Ask the owner of the board before you took it over to transfer the info to you so you can acess the members area (to install updates) and get suport and hacks.
if he dosent know how he sould email
suport@vbulletin.com (i think) or ask at the vbulletin.com community forums

.
also you need to add the copyright notice back to the bottom of your forum, do this by going to the footer template in the admin cp and adding
Code:
<!-- Do not remove this copyright notice -->
Powered by: vBulletin Version $templateversion<br>
Copyright ©2000, 2001, Jelsoft Enterprises Limited.<br>
<!-- Do not remove this copyright notice -->
to the very bottom of the template. thanks.