I see - this is way to make sure it doesn't try to boot to the HD the first time, thereby screwing everything up. Am I correct?
That's exactly right !
To do your method can I simply leave the connector going to the slave (DVD) unhooked and then connect it when I connect the HD?
You could, but there's no point in disconnecting it at any time. You just need to have the hard drive disconnected to avoid an unintentional boot attempt there.
BTW - After I select "Save & Exit" in the BIOS settings will I be prompted to reboot? You said to turn off the system after the install program tells me it can't find a HD. Do you mean shut it down forcefully, i.e. basically pull the plug?
You won't actually need to pull the plug out. Just push in the power buuton and hold it in for about 5 seconds. This should shut the system down completely.
UPDATE - I just read that if I do leave the DVD drive disconnected during the first step, I need to connect the CD-ROM to the connector on the end of the IDE cable. Does that sound right?
Yes, that's right - there should always be a drive connected at the end of an IDE cable. But you don't need to disconnect either of your optical drives, so that's a moot point. Also, since you have 2 optical drives load the XP disk in whichever is the Master drive (CD-ROM).
BTW, this whole procedure is rather complicated and is done only under very special circumstances. If you wre simply installing XP from scratch you wouldn't have to disconnect any drives at all.