Hi guys! I have a late 2009 MacBook Pro and I pretty much love it, the only problem is that I needed more space, so instead of getting a new Mac I bought a WEstern Digital 1TB SATA HD @5400 rpm. After opening the MBP and changing the drive, I used my Time Machine and went to bed. On the day after I was really surprised when I realized that my computer got VERY VERY slow! I mean, with no programs open at all, the annoying raibow ball would appear for more than 10 seconds to open a Finder folder, and with other programs it was even worse. After reading some articles, I decided to format the drive and install the system again (10.6). It took me several hours to erase all the data and after that, I was pretty excited that the installation would go well with an "empty" drive. Wrong again. After choosing the language etc, you hit "Install" button and it appears a message of 30 minutes left. Again I went to bed and the next day I left the installation running...conclusion: after about 20 HOURS it was still like "18 minutes left". I've tried many times following tutorials and instructions, but I really don't know what's going on. I know many colleagues use this 1TB WD with their MacBook Pro's and it works fine...I'm just trying to eliminate all the possibilities before sending it back to Western Digital. Any clue? Thanks guys.