If anyone is interested the SQL2000 equivalent is

USE Master
GO
CREATE PROC dbo.sp_DBA_spaceused_AllTables2
@updateusage varchar(5)='false'
AS
SET NOCOUNT ON

IF @updateusage IS NOT NULL
BEGIN
-- Allow for case sensitivity
SET @updateusage=LOWER(@updateusage)
IF @updateusage NOT IN ('true','false')
BEGIN
RAISERROR(15143,-1,-1,@updateusage)
RETURN(1)
END
END

-- Retrieve the current page size for the OS
DECLARE @KB DEC(15)
SELECT @KB = low/1024.0
FROM master.dbo.spt_values
WHERE number=1
AND type='E'

SELECT
MAX(DB_NAME()) AS DatabaseName ,
MAX(GETDATE()) AS DateSampled ,
U.Name+'.'+O.Name AS TableName ,
MAX(CASE WHEN I.Indid<2 THEN I.rows ELSE 0 END) AS rows,
SUM(CASE WHEN I.Indid IN(0,1,255) THEN I.reserved ELSE 0 END) * @KB AS reserved ,
SUM(CASE WHEN I.indid<2 THEN I.dpages ELSE 0 END
+ CASE WHEN I.indid=255 THEN used ELSE 0 END) * @KB AS data ,
SUM(CASE WHEN I.indid<2 THEN used-dpages ELSE 0 END) * @KB AS index_size ,
SUM(CASE WHEN I.indid IN(0,1,255) THEN I.reserved - I.used ELSE 0 END) *@KB AS Unused

FROMdbo.sysobjects AS O
INNER JOIN dbo.sysindexes AS I ON O.id = I.id
INNER JOIN dbo.sysusers AS U ON O.uid = U.uid
GROUP BY U.Name+'.'+O.Name 
GO