Windows Mobile Developer Power Toys comes with a handy remote display application called ActiveSync Remote Display that allows you to control the device from your desktop. This is great for displaying running demos on real devices or capturing screen shots etc.
The steps to get it working for Windows CE are:
Download and install Windows Mobile Developer Power Toys
Connect the device via ActiveSync.
Start ActiveSync Remote Display from the desktop PC, somewhere in your start menu.
If you just get a blank white screen it means you are missing a file on the device.
You need to copy the correct CPU version of cerdisp2.exe to the \Windows folder on the device.
For CE 4 and higher I use the version for my device (ARM CPU) located on my local machine here:
C:\Program Files\Windows Mobile Developer Power Toys\ActiveSync_Remote_Display\devices\wce400\armv4
Restarting ActiveSync Remote Display should now display the screen from the device with full mouse and keyboard support from your desktop.
One last thing...you may get a warning message about the OS or CPU every time you run ActiveSync Remote Display.
This is displayed because the application is older than the running CE version and is just a warning.