Whilst we are on the subject, I am not a big fan of sub-selects and co-related sub queries, even though the logic that is implemented is vital in many query situations

If you are using SQL2005 or above, you can (almost always) rewrite these as Common Table Expresssions which has the benefit that each can be tested independantly and keeps the main query clean as the CTEs are simply referenced like normal permanent or temp tables and unsually there is no change in the query plan.