As of now not too shabby. As I hoped, once 2.0 and 3.5 then 1.1 went in and accepted all their updates, the 4.0 install prompt finally came from windows update so it appears that preparations have been successful. So far no joy with 1.0, I can install that but the updates fail but might try one more clean install. I'm considering abandoning 1.0 because it's so old I don't really know what uses it these days. I can have the related updates taken off the update list so I don't have to look at that yellow shield anymore. Probably give 4.0 a chance tonight and if it works I'll be doing this all over again to rebuilt framework on my regular machine.
2 hrs or so later I should note that the 1.0 download labeled itself as an Adaware file. I don't know why except maybe Lavasoft had a hand in creating net framework. I also suspected that interference with my current Adaware program was connected to the 1.0 failures so I used Revo uninstaller to uninstall Adaware, again using Ccleaner after every stage. This time 1.0 installed and a prompt for 1.0sp3 came up from MS updates. This also installed correctly so I went ahead and installed Framework 4.0, then the related updates from MS updates and everything, I think, is now up-to-date. So where MS said I had no option but to reinstall the XP OS to fix this relatively trivial issue, I may have figured out a step-wise reconstruction option. Tomorrow I'll do the other machine starting with a full removal of all framework versions. I'll make a restore point first but I don't think there is any need because it didn't help at all last time. If it works I'll make a little tutorial. Again, if I really wanted to stop where I was at, I could hide the failing updates that kept reappearing and at least not be bothered by them, but I'm optimistic that perseverance has paid off.