3D House Icons is a great collection that provides 4 custom, Leopard ready icons featuring 3D houses. The icons come 256x256 and 128x128 dimensions.
3D House Icons set is great if you are looking to give a 3D effect to your desktop.
To learn mode about changing your default Mac OS X icons you can access the Apple Support page HERE. NOTE: 3D House Icons set is free for non-commercial and personal use for software, application, website, blog and etc..