Nice article.
I set up a Quick Search in firefox for this site. You should have a Quick Searches folder in your Bookmarks Menu in firefox and you can add a new search:
1. Go to the folder (I put mine in Quick Searches)
2. Click New Bookmark from the top
3. Enter the following:
Name: Search site:vbulletin.org
Location: http://www.google.com/search?q=site%3Avbulletin.org+%s
Keyword: pick whatever you want - I use "vbo" (no quotes)
Add.
Now all you have to do is type "vbo" and then your search terms into the browsers url text area:
vbo search terms
Hit Enter and it searches just vbulletin.org for those terms.