OK, now I'm feeling some encouragement.
Also, I can buy a full SP2 install disc at Staples, but I'm thinking that because the serial number won't match my original SN, it might complain. But I might be misunderstanding that issue.
If I did buy a full WinXP SP2 install disc from Staples, and booted from it, from your experience with your recent problems, would that stand a decent chance of repairing my SP system, to at least get it to start up?
If not, then I'll try your suggestion of repairing from the original pre-SP1 install disc and then update again to SP2 with the SP2 CD.
Save yourself the eternal problems and buy an Apple.
Somewhere during the second "repair" process Bill Gates wants you to enter the magic number. I don't know what which number you would use or what will happen if you are running a disk other than the original. What problems do you anticipate if you use the original to repair?
I've used my original, SPnothing, to repair my SP2 system. It makes it an SPnothing system which I have to update to SP2. I haven't noticed anything different doing it this way than if I boot from a slipstreamed CD with SP2.
Not much help to you now but it's always good to have a backup to use when this happens. I had backups on other hard drives when my problems started but I didn't want to lose the data between backup and the start of problems. Since only my operating system partition was damaged I was able to save everything I wanted even though I had to make a new XP installation.
Before you try doing an XP reinstall, make sure your hardware is sane.
Download the memtest86 memory diagnostic and burn it to a CD. Boot from it and test your memory.
Next you want to check if your hard drive has bad spots and that's why you system won't boot. No use trying a reinstall if the drive is not in good shape. There are several ways to do this. You could download a drive diagnostic from any of the biggies (Maxtor, Wsetern Digital, etc). You could also download and burn a bootable CD copy of knoppix. You'll be able to read your entire hard drive and see if their are any disk errors.