Running slackware in the command prompt, does that lengthen you battery time since you dont run the GUI?

ummm......I don't think so. Does it seem like it? You need to get ACPI, or APM working to have decent battery life.

i just figured since it is doing much less "work" b/c it is just text than it would not consume so much batter. am i wrong?

I think this only applies if you are using any kind of cpufreq/powernow/speedstep driver to drop down your processor's frequency and by consequence lowering just a little the battery usage.

Anyway, the battery is in order to supply power to processor, hard disk(s), mobo, monitor and other devices, depending whether those are enabled or not e.g. wireless/networking cards, dvd/cdrom drives, usb, parallel, serial ports, speakers, pcmcia/cardbus slots.

So, I don't think you might save any noticeable amount of battery by not running X server. It may vary from brands to brands and models to models anyway.

like raska said, all of the part of your computer are running off the battery. It really depends on how much you are using the battery. If you are compiling something via the console, but are only doing word processing in the GUI, you will use less battery in the GUI than in the console. I think overall however, it won't matter that much which you use.

It makes a difference, but a small one. Compiling with and without X will have different consumptions due to different demands on CPU and RAM. I have noticed longer battery life on Fluxbox than with Dropline Gnome.
Enabling CPUFreq control makes a great difference, though.

It may reduce a little bit, but not considerably.. Given you use something to slow down your processor and ACPI/APM, it comes to what you do with your computer. I keep Windowmaker and KDE on my notebook, and use Windowmaker when I'm on my battery. Using Windowmaker instead of KDE does matter, because KDE is heavier on hardware.