Okay, System Restored to a week ago, combined with MSE scan, finally got rid of it, so it seems. I overcomplicated things, clicking "help" on the after-reboot System Restore page, going through the Help box to the Windows XP Help and Support center, searching through it for an Internet link, opening Firefox through that, figuring out that you need file:// prefixed in the address in Firefox to open computer folder indexes, opening a link to Internet Explorer that way, using IE to open a normal file folder window, and going from there searching for files listed in the "how to remove this virus" page I googled, but none of them existed.
But all I really had to do was click the little "OK" button on System Restore for it to reawaken explorer.exe.
But all I really had to do was click the little "OK" button on System Restore for it to reawaken explorer.exe.