Computerwold in Australia has made this guide for the ones, who are new to Linux and Ubuntu.
Read it here
You can download a complete version of Ubuntu Linux from the Ubuntu website. The ISO (or CD) image is around 700MB. Two versions of Ubuntu are supported: 6.06 and 7.04 — we're using 7.04 for this walkthrough. To follow suit, select Desktop Edition, Ubuntu 7.04.