After the last attempt, I finally got KDE2.2.1 to replace my current KDE2.1.2 desktop!
After the apt-get -t unstable install kde failed, I resorted to using dpkg -i --force-overwrite /var/cache/apt/archive/kde*2.2.1* to force the kde packages to overwrite the other files that had been provided by other packages in KDE2.1.2. I don't remember which packages had given the trouble but teh bottom line is, I've now got KDE2.2.1 running and am busy fixing it to my tastes again! I've also got my kmail and konqueror back too! Now I just hope this all still works after I shutdown my PC tonight! Cheers, John Gay