So I finally got around to re-installing Windows on my computer after it had crashed four weeks ago. A little nudge in the form of renaming the existing WIN.COM into XIN.COM took care of persuading the OEM version to install over the existing operating system.
So now I had a Windows installation that was sort of half-complete -- the start menu was pretty much the way it was before (except that the ordering had gone from the submenus), but most of the programs had some problem or another because they stored data in the registry, which was (of course) hosed by the new installation. Shareware programs had forgotten they were registered, other programs didn't know they had been correctly installed, and so on. Fortunately, my three most heavily-used programs (MUA, news reader, and browser) appeared to work fine -- the first two keep their configuration data in local files.
I don't know whether the file format of the registry is open or not, but that's secondary -- the point is that it's a binary format, and so it's pretty difficult to merge the original data with the current registry, even if I had saved it (well, it's on another partition somewhere inside a big tarball, but I don't want to overwrite the entire registry). Binary configuration files bad, mmkay?