Yes, its possible. Apple recently declared its intention to move to Intel processors in place of PowerPC procs by IBM. So they sent out a few Developer machines to a select number of people to help with the transition of code for the new platform. These machines ran the Mac OS-X (v10.4, tiger) built for intel procs with SSE3, but the OS is still a preview, not a final version. FYI, its quite possible that the final OS-X will still run only on hardware made by Apple. Because Apple is mainly a hardware company and their OS is an incidental product, made to sell the hardware. In effect, all that changed is the processor alone - OS-X will still remain in an exclusive club of Apple customers. But for now, the ray of hope is that the Apple Developer Kit machines ran quite a generic version of the OS, not locked down to specific hardware. Therefore, any processor that supports SSE3 instruction set can run it (meaning the Athlon64, Pentium4). The PC-version of Mac-OS is floating around on P2P networks, being (obviously) a massive popular download. It must be said, though, that its not very easy to get it working - its still a geek toy, and it takes close to an hour, before its all running fine. Is this sufficient info? Enjoy.