I've not long purchased my mac pro ( 4 weeks old ) I have four drives, with OSX and Xp on separate drivers. The past couple of days, the main osx drive has been making a very bad clicking noise. I've read of this forum that this is a sign of the drive failing. Having called my local apple store, and refusing to allow them to have my whole machine for 4 weeks ! They have agreed to allow me to take the drive out and send it to them for repair / replacement. My question is: Will i still be able to boot the computer up onto the XP drive. Or is osx still required for this ? If Osx is still required and i either wait for the replacement or purchase a small replacement in the mean time - can OSX has been installed again on this drive ... without the need to reinstall the XP drive as well? Any words of wisdom would be great. Thanks Anthony.