Wow! That was a close call. I thought I wouldn't be able to sleep tonight because I'd be tossing and turning wondering WHY, WHY
do I have a Kubuntu login screen instead of a Linux Mint Bianca login screen! Then I remembered that to upgrade to Feisty I also had to install 'kubuntu-desktop'. So I removed 'kubunt-desktop' 'kubuntu-settings-default' and 'kubuntu-artwork-usplash'. Now I can control what my login screen looks like with >System Settings>Advanced>Login Manager>Administrator Mode>Appearance. And now I'll be able to sleep.
Linux Mint KDE, Ubuntu Feisty, Debian Lenny, and Gentoo 2007.0
AMD64:AMD64 X2 4800+:4x1GB DDR2
800:GeForce 6150 256MB:ASUS M2NPV-VM:2x320GB