Query to Find time remaining to complete database backup or restore in SQL 2005

USE master
GO

SELECT
          Percent_Complete,
          Start_Time ,
          Command,
          b.Name AS DatabaseName, --Sometimes this will be "Main" as the database will not be accesiable.
          DATEADD(ms,estimated_completion_time,GETDATE()) AS RemainTime,
          (estimated_completion_time/1000/60) AS MinutesToFinish
FROM sys.dm_exec_requests a
          INNER JOIN sys.databases b
          ON a.database_id = b.database_id
WHERE
          Command like '%Restore%'
          OR Command like '%Backup%'
          AND Estimated_Completion_Time > 0