The screen saver on the Eee PC is set to blank the screen after 5 minutes in Easy Mode. There's no apparent way to adjust that time-out setting. However, this is Linux, so there is a way!
Open a Terminal Mode (type Ctrl-Alt-T) and type:
sudo nano /etc/X11/xorg.conf
Then find this section in the file:
Section "ServerFlags"
Option "AllowMouseOpenFail"
Option "BlankTime" "5"
Option "DontVTSwitch" "false"
Option "AIGLX" "false"
EndSection
Finally, change “BlankTime” to the time in minutes to wait before shutting off the screen and save the file (Ctrl-O).
Another way is using the KDE control center:
In Easy Mode, open a Terminal Mode (type Ctrl-Alt-T) and type:
sudo kcontrol &
Enter your normal password when prompted. If you are in Advanced Mode, just start up Control Centre. And if your Control Centre seems to be missing all of its modules, see the “Recovering from an Oops” section at the bottom of the wiki page on adding xandros repositories.
Once in the Control Centre, select Display > Screen Saver, and adjust the time Code TextCode Textdelay your prefer. You can optionally require a password to turn the screen back on. Ensure you also check the “Make aware of power management” box.
Now select Power Management > Power Control, and check the box for “Enable display power management”. Set the top sliders all the way to the left to disable them, and then slide the bottom slider (“Power off after:”) to the same value as your screen saver. This will ensure that not only does your screen blank the screen, but also the power to the LCD backlight will be cut off. Your Eee PC will not power down after this delay, and will continue to run.