I have an Athlon X2 desktop (Windows XP x64) and a Powerbook G4 laptop (Mac OS 10.4.8). Being a student in acoustical engineering, it helps to have access to both platforms, because of the variety of Windows-only software (e.g. EASE) and MacOS-only software (e.g. Digital Performer) that I need to use. These days a Macbook Pro would be the optimal solution, but when I started a year and a half ago, the Intel-based Macs weren't out.