The second thing I'd do is take the nolock hints out. See - http://blogs.msdn.com/b/davidlean/archive/2009/04/06/sql-server-nolock-hint-other-poor-ideas.aspx

If the sort has to be there and is the most expensive portion, there's not really much (other than more hardware) that can be done. Can't leverage indexes because the columns are in 3 different tables.