Agree with last poster. Basically, DELETE TOP 1000000 FROM EVENT doesn't work, but DELETE TOP (1000000) FROM EVENT does. Similarly ROWCOUNT works, but the former (TOP), has the benefit that you can use a variable. So one of the statements is very misleading, except if you're using SQL Server 2000 - when DELETE TOP (1000000) won't work.
Although this tip is useful for me, as I have groups of tables I have to delete in chunks and order of last ID in the same sequeunce across the sets of tables.
This DBA says - "It depends".