I'm just about to upgrade my Macbook's hard drive to a nice big 250GB drive, and wondering what to do with my old 100GBish drive. I figured I could just use it for storage or buy an external enclosure for it or something, but then another idea hit me.... There's only one thing that I always have go back to Windows for, and that's recording music with lots of Windows only apps I've bought and continue to use. So I was wondering, if I were to install ONLY Windows XP on my 100GB hard drive, is there a way that I could have my Macbook boot into XP every time the hard disk was present? i.e. could I select my operating system based on which hard drive was present in the laptop? And, if I could do this, is there any way I could boot my system from the Windows drive externally? i.e. can you 'hold a button' or something on system boot to make it load its OS from an external source? That way, I could have an entire disk reserved for Windows and music apps....any ideas?