This guide was originally written under VirtualBox v3.1.4 environment.

The support on Mac OS X guest is greatly enhanced in VirtualBox (in fact this is the first time that Mac OS X guest is supported). As a result, it you want to run Mac OS X (no matter it is Leopard or Snow Leopard), I suggest you to setup your virtual machine under VirtualBox v3.2.0.

Refer to the updated guide here.