hd light always on

Hi everyone, Ive just installed suse 6.4 on a halfway decent machine and everything went well, only problem is my hd light is always on! Ive got Linux on a 3 g partition with 100m swap 98 m ram I've never seen the light on that machine stay on, it donst "sound" like there is any activity... but it makes me nervous. If I look on the performance mon in K all processes seem to be fine. thanks rob