CPU usage of each active sessions?

Hi all.
OS : WIN2000 SERVER
DB : ORACLE 8.1.7
Task manager in NT/2000 display cpu usage for processes and can not display cpu usage for threades of one process.
Can anybody tell me which tools (In NT/2000 or oracle) can display cpu usage for active sessions(user&background processes) that are threads of ORACLE process.

-- sorry for my english.
best regards.

Maybe you can obtain so that you want with Oracle Performance Manager.

Hope that helps

Angel

Maybe this is what you're looking for:
---
select disk_reads,substr(sql_text,1,1000),username
from v$sqlarea a,v$session b
where a.address = b.sql_address
order by disk_reads desc
---
Thanks

Thanks friends.
More Info :
My server (compaq proliant 7000) has 4 CPU and 3 CPU assigned to ORACLE process.
Sometime one(or more) bad query causes 3 CPU reach
%100 cpu time , and I want find bad query. in this situation oracle tools(like OEM or even SQL*PLUS) runs very slow , and I want OS tools(command) for finding session(s)(threads) that consume all CPU.
I now using Top Session in OEM for finding session(s) that use more CPU in this situation.
But what is different between this 2 item in user statistic filter :
a) CPU used by this session
b) recursive CPU usage

-- sorry for my english

Best Regards.