I have a CD MacBook that I'm looking to upgrade. I replaced the HDD with a WD 750GB that I really like and plan to keep for the new MacBook I'll buy. I have an older 250GB HDD that I used in this MacBook before. I'm going to do some zero-out erasing. The questions I have are... Can I go ahead and install Snow Leopard on this HDD? It's in an external enclosure. This way when I do sell I can just swap out the drives and be on my way. I'm guessing no, just in case there's an issue with the install process. Next question is should I install Snow Leopard or the original Tiger that went with it? And when I do install, would I do a complete install with all additional languages or just basic stuff? It's a large enough HDD that a basic user wouldn't notice that stuff. A power user would probably erase it (after watching the start up video).