Watch out with those clustered indices...the order is NOT guaranteed to be the index order.

There are a few cases - out of disk space is one I experienced, parallel query execution et al - that cause the leaf data to be out of order.

See also http://blog.sqlauthority.com/2007/09/24/sql-server-order-of-result-set-of-select-statement-on-clustered-indexed-table-when-order-by-is-not-used/