Data File Size

SELECT size_in_mb,used_size_in_mb,size_in_mb-used_size_in_mb as free_in_mb FROM (
SELECT cntr_value/1024 size_in_mb ,
(SELECT cntr_value/1024 FROM master..sysperfinfo WHERE counter_name='Log File(s) Used Size (KB)' AND instance_name='mydb') used_size_in_mb
FROM master..sysperfinfO WHERE counter_name='Log File(s) Size (KB)' AND INSTANCE_NAME='mydb'
) a

I need to store totalsize,usedsize,freesize of the datafiles in a table to get an average of how much my datafile has increased over a week.
The above query i am using is for logfile size. Can any one help me with datafile size plz.
I've checked sp_helpfile, sysfiles but couldn't find what i am lookin for(used and free space). EM in taskpad view for a database shows the statistics for the datafile. I've tried a trace to find out a stored procedure but couldn't!!!
May be i am unaware of a simple stored-procedure that can do this for me.

Howdy!use master
go
sp_helptext sp_spaceused
go

Maybe you will get some ideas from here ... am a little busy ... so just help yourself ...|||You can use code from sp_spaceused to make your own logic ...|||use master
go
sp_helptext sp_spaceused
go

Maybe you will get some ideas from here ... am a little busy ... so just help yourself ...

Thanx for guiding; i would try.

Howdy!