Are you looking for something like this?

CASE WHEN Sum(poitem.qty_ordered) = Sum(poitem.qty_received) AND Sum(poitem.qty_voucher) = Sum(poitem.qty_received)

THEN 0 ELSE 1 END

Are you aware on what the NOLOCK hint does? Are your users aware that they can get inconsistent results? Are they fine with that? Do you know that it's not a go-fast option?

http://blogs.msdn.com/b/davidlean/archive/2009/04/06/sql-server-nolock-hint-other-poor-ideas.aspx

http://www.jasonstrate.com/2012/06/the-side-effect-of-nolock/

http://sqlblogcasts.com/blogs/tonyrogerson/archive/2006/11/10/1280.aspx