KDE and Virtual Desktop Size

Sun Mar 11 23:49:57 UTC 2007

My laptop display is set at 1440x900, this is also the size of the desktop.  
When I attempt to resize the desktop to 2880x1800 (4x the original size) via 
xorg.conf, x server places the KDM login window exactly on the bottom right 
corner of the screen (showing only the upper right corner of the login 
window).  When I log in to GNOME, I can set the virtual desktop size within 
GNOME itself, not X11.  Any such utility for KDE?  I would like to see what 
the effects are of having a desktop larger than my actual monitor resolution.