Well, after much trial and tribulation (tried to update to 10.04, had more bugs than you can hit with a flyswatter) I reinstalled and got WUBI working for 8.04. I decided this was secretly brilliant because I found a website explaining that you could use LVPM to bootstrap a WUBI installation into a full installation, but only using version 8.04 or earlier. I back it up - this time from the Windows side so that if I get unrecoverables on the Unix side, I can just restore it with DriveXML.
This is okay, I think. I try to use GPARTED to move on from there toward my dream of having a current version of Unix dualbooted with Windows. It doesn't work because you can't alter the partitions on a running hard drive, but it takes me a long time to figure this out despite a friendly message in bold at the top of the GPARTED documentation page because I basically know nothing about partitions or altering them. I am not using a LiveCD because (as we know) the CD drive is not working.
Today I think, well, I've got something pretty close to what I want. Maybe I'll just let it rest. Then I notice a little icon on the left side of the screen that says Audio CD. Yes! My CD/DVD drive has come back for one last fling! I can't find the Ubuntu CD I burned just a few days ago so I make a new one.
It sounds so hopeful, doesn't it? Well. I got unrecoverable errors during install three times, even after I had done the fix of turning off the floppy drive boot option in BIOS that I found on the support forum. Each time, I then tried to install it from within the desktop. The first two times it bogged down when I tried to repartition, but I didn't give up. (First it gave me a partition writing error, then it only offered to erase the whole disk rather than changing the size of the Windows partition.) The third time I just took the suggested partition and went with it. If I can get it on the disk at all then I can fiddle with the sizes later, by hook or by crook.
Now it is into the actual install. The actual install! 58%! I am very hopeful.
If this doesn't work, I'm no worse off than I was before. (I hope.) I have Windows installed with WUBI 8.04, I have a complete hot image backup that should work assuming I can get the computer to start at all.
If this does works, first I will back it up so I don't have to go through this again very soon. But I find that regardless I am still not unhappy about the time I spent on all my various installs and upgrades. It was actually a great refresher in Unix and a great introduction to how Ubuntu works. Plus it was sort of fun.
ETA: YESSSSSSS, it worked!