I ran Scannow and although it took a while, it completed (no message requesting the Windows CD). But when I tried running Silent Runners I got the same error message telling me to start the WMI service. Still can't open "Services".

Next, I did as shown in udatexp.com/scannow-sfc.html and copied the I386 file from my Windows XP installation CD to drive C (the I386 folder already existed so I overwrite all files with same name) then rebooted. Ran Scannow once again, rebooted, but still can't run Silent Runners or access the "Services" to start WMI.

Sorry this is proving to be such a pesky problem. I really appreciate the help and am learning tons!

I don't know why yours is not working, but I have found someone with the same problem Try the suggestions here;
http://www.mcse.ms/message579903.html and let us know how you go. You may end up having to do a system repair.

There were a ton of links in the discussion link you provided [mcse.ms/message579903]. I've been going through all of them, researching and trying numerous solutions.

One I found on MS Help [Article ID: 912651] had some strong similarities (missing ATL.DLL file), but when I tried to type in the "solution text" it gives me an error that it can't find a file.

I tried everything explained in the mcse discussion (with the same negative results) except the very last item:

If you have a real XP CD, find services.msc & fsmgmt.msc,
they live in: C:\WINDOWS\system32. rename 'em to:
services.old & fsmgmt.old. Reboot.

It sounds like I would be renaming these 2 files on my hard drive (not on the XP CD) but this wasn't clear to me exactly what to do. If you think this is something I should try, perhaps you could give me some more clarity on exactly what I need to do.

Anyway, I've spent so many hours on this problem that I'm ready to try something more drastic if necessary.

What is a "system repair" and what does it involve, is that the next step?

Thanks for your help!

If I were you now, I would be doing a system repair job. There is an excellent tutorial here http://www.michaelstevenstech.com/XPrepairinstall.htm so rather than explain it all here (not that I could ), it is probably better that you go there.
Take note that you will have to get all your M$ updates again.
The good thing about a system repair is that you do not lose any of your programs/files.