The Halo World project is supported by NASA grant NAG5-4203. Part of the research reported here was performed using the Intel Paragon system operated by the Center for Advanced Computing Research at Caltech; access to this facility was provided by Caltech. We also acknowledge computing resources provided by the Australian National University Supercomputer Facility. DWP acknowledges support from an Australian Postgraduate Award, a Caltech Graduate Research Assistantship, and a European Southern Observatory Studentship.