I have a spare pc, it has windows home already preinstalled on it.
I would like to add an additional operating system (Linux) to this pc.
I know you need to partition the hdd and use (Grub?) but I do not know where to start.
Please help.

Thank you.

Here are a few guides:

http://www.google.com/search?hl=en&s...l+boot&spell=1

Here's a link to the Linux Newbie that may answer a lot of your questions, Newbie Guide

Also if you are looking for a good friendly distro, you may want to try PCLinuxOS 2007. The down load will give you a live CD. You can then boot linux from the CD without installing to see if you like.