PlanetX64 explains how they managed to install Mac OS X on a MSI Wind U100 netbook:
Recently I've managed to install Apple's OS X Leopard operating system 10.5.4 onto a 10 inch MSI Wind Netbook, and you can too. Let me preface this by saying that I consider myself an Apple fan, and run nothing but authentic Macs in my home studio office. If you're looking for another Mac vs. PC debate, then there's is nothing for you to see here. Move right along please.
The Victim: An MSI Wind U100 Netbook. This slick little machine comes preloaded with your choice of Windows or Linux. Armed with an Intel Atom 1.6 Ghz Processor, 1 GB RAM, 80 GB HD, built-in ethernet, wifi, webcam and bluetooth. That said, the most enticing feature is its crisp & clear 10 inch screen.