Temp tablespace usage Oracle 9i/10g

Below is the query that I would use to find out usage of temp tablespace:

select
  df.TABLESPACE_NAME,
  df.df_size/1048576 AS TOTAL,
  nvl(us.free_sum, 0)/1024/1024 AS USED,
    (df.df_size/1048576 - (nvl(us.free_sum, 0)/1024/1024)) AS FREE,
    df.FILE_COUNT
from
    ( select TABLESPACE_NAME,
            sum(bytes) as df_size,
            count(TABLESPACE_NAME) AS FILE_COUNT
     from dba_temp_files
     group by TABLESPACE_NAME ) df,
    ( select TABLESPACE,
            sum(BLOCKS)*(select value from v$parameter where upper(name) like '%DB_BLOCK_SIZE%') free_sum
     from v$sort_usage group by TABLESPACE ) us
where df.TABLESPACE_NAME = us.TABLESPACE(+)
order by TABLESPACE_NAME;

Sample output:

TABLESPACE_NAME                     TOTAL       USED       FREE FILE_COUNT
------------------------------ ---------- ---------- ---------- ----------
TEMP                                 1024          0       1024          1