I have a 2.5 GHZ Macbook pro17" - i want to upgrade the hard drive - so i went today and purchased a 320gb Western Digital scorpio black 7200rpm drive. Install went fine, OS Loaded fine. but using the OS was torture, spinning beachballs coming up randomly - it would happen for a few seconds, and just freeze the whole system until it came back.. So i pulle dthat drive and put the OEM drive back in, no problems. Does anyone have any suggestions on drive replacements for my machine? Never really had these problems in the past. Thanks in advance!!