There's no single Right Way to partition; it depends on what the machine will be used for, and on your personal preferences.
Here's an article with a brief discussion on partitioning schemes for a personal workstation, and a sample breakdown for a 10G drive.
You probably don't need the whole drive to start with, so you might want to reserve some of the drive as a separate partition for use later on (a place to store clutter, er, I mean MP3s, install another distro, etc.)
Help partition sizes?
