Auditing Sessions (too old?)

I am not too familiar with how to audit sessions running my DB. Should I be concerned about OLD sessions? Or sessions that I do not know what they are doing? Any advice is appreciated. The following is an example. It's been running thru sqlplus on the server side since 11/03/2000 (sorry for how it looks on this forum):

SADDR SID SERIAL# AUDSID PADDR USER# USERNAME COMMAND OWNERID TADDR LOCKWAIT STATUS SERVER SCHEMA# SCHEMANAME OSUSER PROCESS MACHINE TERMINAL PROGRAM TYPE SQL_ADDR SQL_HASH_VALUE PREV_SQL PREV_HASH_VALUE MODULE MODULE_HASH ACTION ACTION_HASH CLIENT_INFO FIXED_TABLE_SEQUENCE ROW_WAIT_OBJ# ROW_WAIT_FILE# ROW_WAIT_BLOCK# ROW_WAIT_ROW# LOGON_TIM LAST_CALL_ET PDM FAILOVER_TYPE FAILOVER_M FAI
-------- --------- --------- --------- -------- --------- ------------------------------ --------- --------- -------- -------- -------- --------- --------- ------------------------------ --------------- --------- ---------------------------------------------------------------- ---------- ------------------------------------------------ ---------- -------- -------------- -------- --------------- ------------------------------------------------ ----------- -------------------------------- ----------- ---------------------------------------------------------------- -------------------- ------------- -------------- --------------- ------------- --------- ------------ --- ------------- ---------- ---
82599C78 19 653 167668 8258284C 5 SYSTEM 0 2.147E+09 INACTIVE DEDICATED 5 SYSTEM oracle 10584 shamrock pts/15 sqlplus@shamrock (TNS V1-V3) USER 8348B404 3.760E+09 8348B404 3.760E+09 SQL*Plus 3.670E+09 4.030E+09 32295 -1 0 0 0 03-NOV-00 3704674 NO NONE NONE NO

Strange. I guess if they are inactive since a long time, you could kill the processes. Another option would be to bounce the db in order to shutdown the processes cleanly.

Maybe you can use the next view to determine if you can cancel a certain session.(NM : nusmber of minutes )
It returns the sid of all the sessions that have been inactive for NM*60 seconds.

select v.spid
from v$session s,v$session_wait w,v$process v
where
s.sid = w.sid and
v.pid = s.sid and
seconds_in_wait > &NM * 60

Hope this helps
Gert