I don’t use xscreensaver (or for that matter gnome-screensaver, which is rudimentary at best). That’s because I’m an Openbox fan, and the idea of an additional daemon running in the background, waiting for me to do nothing … well, it offends my sense of efficiency.
So I live without it. But to be honest, the default X timeouts under Edgy are way too long. I think the screen times out at 10 minutes, and the backlight is powered down at 30. I’m not 100 percent sure on that since I can’t find what sets them, but those numbers seem right. They’re very long.
If you want to set them to something shorter, you can use
xset dpms from a terminal, but that won’t hold on reboot. Editing your xorg.conf file is a better way.
Under the “Monitor” section, add this:
And under the “ServerLayout” section, add these lines:
Option "BlankTime" "3"
Option "OffTime" "5"
Those variables set the time in minutes it takes the screen to go blank, and the time it takes for screen (or in my case, the laptop panel) to be turned off completely. Restart X, and see if you like the results.
There’s a more extensive (though slightly dated) explanation here.