Find Largest size Tables in a Database

IF EXISTS 
    (
SELECT 1 FROM master.dbo.sysobjects 
WHERE name = 'sp_LargestTables' AND type = 'P'
    )
DROP PROC sp_LargestTables
GO

CREATE PROC sp_LargestTables(@n int = NULL,@IsSystemAllowed bit = 0)
AS
/*=========================================================================
CREATE DATE:Hari N Sharma
CREATION DATE:10-09-2007
LAST MODIFICATION DATE:11-10-2007

PURPOSE: To get a list of User/System tables according to their size.
=========================================================================*/
BEGIN
SET NOCOUNT ON
DECLARE @LOW int
SELECT @LOW = LOW FROM master.dbo.spt_values (NOLOCK) WHERE number = 1 AND type = 'E' 

IF @n > 0 SET ROWCOUNT @n

SELECT TableName,[Row Count],[Size (KB)] FROM 
(
SELECT QUOTENAME(USER_NAME(o.uid)) + '.' + QUOTENAME(OBJECT_NAME(i.id)) AS TableName,SUM(i.rowcnt) [Row Count],
CONVERT(numeric(15,2),(((CONVERT(numeric(15,2),SUM(i.reserved)) * @LOW) / 1024.0))) AS [Size (KB)]
FROM sysindexes i INNER JOIN sysobjects o (NOLOCK) ON i.id = o.id AND 
((@IsSystemAllowed = 1 AND o.type IN ('U', 'S')) OR o.type = 'U') 
WHEREindid IN (0, 1, 255)
GROUP BY QUOTENAME(USER_NAME(o.uid)) + '.' + QUOTENAME(OBJECT_NAME(i.id))
) AS Z
ORDER BY [Size (KB)] DESC

SET ROWCOUNT 0
END

GO