This will show you the longest running SPIDs on a SQL 2000 or SQL 2005 server:

select
    P.spid
,   right(convert(varchar, 
            dateadd(ms, datediff(ms, P.last_batch, getdate()), '1900-01-01'), 
            121), 12) as 'batch_duration'
,   P.program_name
,   P.hostname
,   P.loginame
from master.dbo.sysprocesses P
where P.spid > 50
and      P.status not in ('background', 'sleeping')
and      P.cmd