Hi,
Any computer (really) A-N-Y computer) can run Linux, or better, Linux does not need massive resources to run. Example? I installed a print server on my LAN: P3/320Mb/10Gb/Lan, annother example? A web server P3/254Mb/40Gb/Lan.
Linux can run on Macbooks or plains, no sweat.
Interested? Read a review before you get Linux, helps you choose:
http://www.linuxforums.org/articles/overview-of-the-ten-major-linux-distributions_92.html
I used Fedora, Ubuntu, CentOS, Debian and Arch. For a starter like you? Use Ubuntu,( http://www.ubuntu.com/desktop/get-ubuntu/download ) helpfull and easy goin'. Have a lite/older PC? Use puppy Linux (get it on http://puppylinux.org/main/index.php?file=Overview%20and%20Getting%20Started.htm )
Stuck? The Linux community helps, on www.linuxquestions.org - hey, maybe I can even answer some questions!
Wellness!
Thor