The performance benefits of dual-core AMD processors over single-core processors will be obvious to end users, and the company has unreleased benchmarks to prove it, De Onis says. Those benchmarks, however, were completed running the 32-bit version of Microsoft?s Windows XP SP2 operating system, not the new 64-bit Windows XP x64 operating system that was released just last week. ?We haven?t run those benchmarks yet,? De Onis says. ?We needed to get the official [Windows XP x64] release.?