Thanks buteman. I've installed the 30-day trial of Revo, and it's looking good. It couldn't uninstall Lotus because it relies on Lotus' own installer to do that part of the process, so I've deleted all the Lotus files manually and now Revo has gone on to stage 3 where it's presented me with a list of all the redundant and/or incorrect registry entries so I can pick the ones to delete. Thanks for the warning about selecting only bold black entries.
I tried RegCure earlier, but it requires me to pay if I want to remove the 300+ errors it detected :-(