I had to read over that post so many times to understand what you meant. :(
There's already a feature to do that, Cheesymitten. The search feature, in my opinion, when it comes to vBulletin... isn't as good as it could be. If you search using the quick search bar at the top, sometimes you'll be led to a page of results and sometimes you won't be.
Depending on some of the terms you use in your search, you may find it and you may not. But the search bar at the top searches every word you're looking for in posts and titles. For example, I searched for the thread title Serious Discussion and Debate and it led me to the thread posted yesterday, suggesting that be added to the community. I searched for your thread title, and it led me to
the search page. Now, under the Search by Keyword, you would enter the search in, and select from the drop down "Search Titles Only," where of course it would only search the titles of the threads that you could possibly be looking for.
So to answer your question, it searches both the titles and the content in the posts, but isn't always as accurate as it can be depending on what you're searching for and the keywords you use in your search.