2. During the Leopard install, you are given the option to create specific partitioning to accommodate M$ Vista and Linux. Reformatting your HD is not required. Depending on your processor and RAM, all OS’s can run simultaneously & independently. A (minimum) 150 GB HD is required (250 GB is recommended), and 2 GB RAM (minimum) should you wish to run more than one OS. Dual processors are required for optimum performance, though this may change in 10.5.1 or 10.5.2.