The Mac that I am using is an Intel iMac 1.83 Ghz with 512MB of RAM and 160GB hard drive. I am using the latest version of vmware Fusion and an ISO for Debian version 4.0 also known as etch. I downloaded the i386 netinstall iso file from www.debian.org.
Read it here
I started with a new virtual machine. I selected Linux and then Ubuntu. The usual setup really for the rest of the settings. I gave the machine 124 MB of RAM to start off with and set the machine to boot from the ISO image that I downloaded.