Xorg upgrade: Getting twm not kde

["Edward C. Jones" <edcjones@comcast.net>]

I use a PC with an AMD Athlon64 3500+ chip and Debian unstable, i386 port.

At about 6 PM (EDT) on April 15, 2006, I used synaptic to upgrade my 
system. When I enter "startx" I now get some simple window manager 
instead of KDE. An article in debian-user suggested that X was using 
/usr/lib/x11/xinit/xinitrc. This seems to be correct since I am getting 
the three xterms and a clock mentioned in that file. Therefore I am 
probably in twm.

I want "startx" to start KDE. Which config file changes do I need to make?

How do I exit twm?