I bet the site sold lube but was not of the Jiffy variety.
I
knew the website would amuse some folks when I wrote it . . . was just wondering who'd be first to comment. Sure enough, it was our scapegoat . . . and never_retreat followed close behind.
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In any case, reinstallation using the original CD seems to have mostly worked - a few minor burps during repair (e.g., prompting me to find a particular file) but in due course the computer began booting normally again. Of course, it only had IE6 which was a bit balky, though Firefox worked OK. Updated AVG, Malwarebytes, and Spybot S&D and ran all scans with no nasties found. Other programs (Excel, Photoshop, Cadkey, DVDFAB, etc., all worked OK.)
IE8 downloaded via Firefox didn't install for some reason, but I managed to get to Windows Update indirectly with IE6 and got SP3 and IE8 installed, so now the browser is working. Of course, there were 90+ updates to install . . . got a bunch this morning before work, but still have about 70 to go. What fun!
Still, I'm glad I kept important data (Tax forms, budget spreadsheets, etc.) on separate hardcopy media.
Thanks to Jim, Brad, and Lee for their advice.