Last night I went to download the update for WoW. Anyway, my hard drive and fan seemed to be spinning very high. Towards the end of the download, I heard a "whirring" or "whistling" sound, which sort of faded in, got a little loud, and then faded out. It did it about 3 different times, but hasn't done it since. Is this an indication that something is wrong with my hard drive? Or could it have been the cooling fan? My first hard drive that crashed would give me a clicking sound, but this was a high-pitched whirr or whistle. Any ideas?