Do you experience any memory issues ?
have you checked the cache too? is it playing well ?
another thing , is you log files are sitting with tempdb files ?
Also , Check following events at perfmon
% Disk time= ?
% Disk read time =?
% Disk write time = ?
Avg disk queue lenght = ?
PLE = ?
-------Bhuvnesh----------
I work only to learn Sql Server...though my company pays me for getting their stuff done;-)