After the usual routine (get kids to school, take care of a few errands and house stuff, go for a walk, talk with R., meet T.'s van, shepherd T. off with J., etc.), I said to myself, Self! It is Time!
So I went upstairs and fired up the ancient iMac to try to figure out why I felt so uncomfortable just deleting everything and finding someone who is willing to take it, ideally without me having to pay them to do so. And I figured it out quite quickly. After comparing the picture files on the iMac's drive to the ones on my CD archive (and noting the legend on the CD archive, which strongly suggested the existence of a second disk that has gone completely missing), I realized that there were a bunch of photos that needed to be extracted from the iMac, archived and loaded up onto Flickr.
So that was a project. After fiddling around for a while and being horrified at the prospect of excavating the zip drive, I realized that I could just put it on a zip drive and sneakernet it downstairs to the laptop, where I could then burn it and upload it. Tada! This is very cool, because one of the missing files is the digital original of one of my all time favorite pictures of my husband. It's been printed out and up one place or another for years, on and off, but I could not for the life of me find the original file.
There are some other files to think about saving, but a lot of the pressure to get stuff off the box has been relieved. I think one more shot at this tomorrow, and I can move it out of my life.