Turn Somewhat Old Laptop Into a Server

[Xomphos]

Hey,

I got a used, somewhat old laptop a while ago. The specs include:
-1.4 or 1.6 GHz Intel Pentium 4
-30GB HDD
-256 MB RAM
-Wireless-G WiFi Card
-The battery is still good, just lasts 20mins-1:30hrs depending on usage/OS installed on it.
-Windows XP
-Dell Brand
I used it a lot when I got it, at the time it was pretty good since my desktop PC was only a bit better (could play a bunch of games); however, I recently built a new desktop PC that cost around $500 or so and can play a lot of games just to show how powerful it is.
For a while, the laptop has been sitting in its case in my closet not being used. Is there anything I can use it for? What do you guys do who have a laptop as a secondary computer? I don't travel much so it's not that great there. Also, I don't want to spend money on upgrading it right now. Any ideas? I have now been thinking of turning it into an always-on server file-server. Would this be a good idea to do? Is there a good way to do this under Windows XP? I have installed Ubuntu on it before-in fact, it preformed better I believe, but setting up the wireless was a pain along with other software. Also, could I turn the screen off somehow while it is running and maybe even close the lid? Also, how much power would this take? Does an older laptop like this use a lot of power?

So, any ideas?

Thanks!

[Dr Small]

If you have bandwidth to spare, set it up to seed ubuntu torrents, or setup a webserver on it. That would be my first guess.

[Tundro Walker]

When I checked CraigsList for a used laptop recently, seems everyone selling one meeting your laptop's specs would try to hock it for $400. So, why not just sell it. You could almost recoup the cost of your new desktop.