Hello there, I am buying a Western Digitial (probably) External Hard Disk Drive today. It will either be 250GB or 320GB, depends on how much money I'm going to have with me. I wanted to know what the best way to format it is so it can be 'read and write' on both Macintosh and Windows in the same time. But if that's not possible, then at least Windows only (Windows 7) since that's what I use for games and now games are in huge sizes, just got Call of Duty 6 and it's like 11GBs. Thanks a lot and have a nice day. Tarek.