And Expanding on Mohammed Excellent idea:

DECLARE @SQL  NVarchar(4000)

if OBJECT_ID('tempdb..#T1') IS NOT NULL

 drop table #T1

create table #T1 ([name] varchar(60)

  , [rows] varchar(11)

  , reserved varchar(11)

  , data varchar(11)

  , index_size varchar(11)

  , unused varchar(11)

  , DBName nvarchar(128))

SET @SQL = ' SET NOCOUNT ON '

SELECT @SQL = @SQL + ' INSERT INTO #T1 ([name], [rows], reserved, data , index_size  , unused ) EXEC ' + NAME + '..sp_MSforeachtable @command1=''sp_Spaceused''''*'''' '', @replacechar=''*'', @PostCommand='' Update #T1 Set DBName = N'''''+ NAME + ''''' where #T1.DBName IS NULL '' ' + Char(13)

FROM  MASTER..Sysdatabases

WHERE dbid > 4 --exclude system databases

EXEC (@SQL)

--Print @SQL

SELECT *

FROM #T1

ORDER BY DBNAME,[Name]

Will give what you want !!!