Query for finding the data and log file space usage in a Database

Select a.FILEID,
[FILE_SIZE_MB] =
convert(decimal(12,2),round(a.size/128.000,2)),
[SPACE_USED_MB] =
convert(decimal(12,2),round(fileproperty(a.name,'SpaceUsed')/128.000,2)),
[FREE_SPACE_MB] =
convert(decimal(12,2),round((a.size-fileproperty(a.name,'SpaceUsed'))/128.000,2)) ,
NAME = left(a.NAME,15)
from
sysfiles a
Thanks
ASR