I have two Western Digital hard drives stacked on top of each other in my system. The one on top is a 40GB UATA100 drive at 7200rpm. The one on the bottom is a 100GB UATA100 drive at 7200rpm. I used to use the 100gb in a different computer, but I noticed that ever since I put it into this system, its been running loud and with low, high pitched noise. I opened my case after my system had been on for about 4 hours, and both hard drives are burning hot. The 100gb on the bottom is even hotter than the 40gb on top. I think the 100gb is not getting enough ventilation because of it being sandwiched by the 40gb. I've looked around and these stores sell these so-called hard drive coolers, with fans that cool the drives. Do these work, and are they necessary?? My case is a Gateway case, so I would think that they thought of cooling issues with hard drives stacked on top of each other...