Laptop power management
Does anybody have a link to a decent power management howto directed at laptops?
I'm trying to increase the battery life on my laptop (Compaq EVO N115), and need a few basic suggestions. I've already turned the LCD brightness down to minimum. I want to power off the DVD and floppy drives, and if possible underclock the CPU. Right now, it lasts maybe an hour, and I'm pretty sure it's because the CPU isn't underclocking, because in Win it lasts about 2.5 hours.
The kernel supports CPU underclocking, and the CPU which is 1.2GHz normally will underclock as low as 495MHz with PowerNow, so is there a command or program that I can use to force the thing to underclock? I know that KDE's battery monitor will do it, but I'm using XFCE, and ideally I'd like to underclock the CPU full time, and only turn the MHz back up when I need it (I want this to be manually set). The default seems to be the other way around: running at 1.2 full time, and clocking down when it thinks I don't need it.