Where I currently work we are still using SQL Server 2000 in production!  Recently I needed to produce a hierarchical report with data from numerous joins.  The process of taking data from SQL 2000 via FOR XML AUTO and then transforming it with XSLT was painfully slow.  It took well over a day of dev time to produce a framework that would allow easier changes in the future.  If we could move to SQL 2005 then we could take advantage of XQuery as outlined in this article SQL Server 2005: Intro to XQuery.  Using XQuery I think the same results could have been achieved in less than an hour.