OK following feedback on the search, I've enabled some more advanced search features. You can see them documented here:

http://dev.mysql.com/doc/refman/4.1/en/fulltext-boolean.html

Provided they don't kill our database server, they should be sticking around.

In particular, you can use quotes to match an exact phrase, you can use + before a keyword to insist that it's always present or - to insist that it's not present.

Let me know if this improves things...