I have now migrated this website to WordPress 2.5. Better yet, my installs are now managed with Subversion, which will make future updates as easy as issuing a single command from my web-server command line. This all comes thanks to a handy article in the WordPress Codex that gives step-by-step instructions.
This new install was done in a virgin folder (for subversion’s sake), and I had to copy existing files over to the new location. If you spot any breakage, please let me know and I’ll fix it.