Today, while I did my Day Jobbe on my work computer (naturally enough), I had the personal machine sitting to one side as I installed applications, configured them, and eventually copied my data back from the other non-booting 320GB drive. I think I've got everything saved that I want saved. My documents are also backed up onto the large "brick" external hard drive. I moved more photos and videos onto DVD-ROMS (that's effectively an additional backup since they're also on the "brick." So I'm almost at the point where I can clone the drive, which has now booted dozens of times since just about every application wants to reboot the computer after installation, and some want to do it multiple times. I'm going to clone it into the other non-booting 320GB drive and say goodbye to whatever was on that drive before.
One new wrinkle this time: I've told my drive-cloning software, Total Recovery Pro, to put in a system recovery trap at boot time. So after POST I get a simple black screen asking if I want WinXP or the TRP Recovery Console, which is a self-booting copy of TRP separate from Windows proper. I don't know if this will make any difference, but I'm going to give it a try.
Meanwhile, I also bought another used machine on eBay and had it shipped to Oregon so that it will be there when I get there this weekend. And I'm carrying a crate of computers and hard drives with me. Some of these machines should work.