I imagine that my system must use a 64-bit processor to use 64-bit software, and with that the whole motherboard and all hardware must be 64-bit capable—is that so? Or can I install a 64-bit OS on any system, regardless of the hardware, processor, and motherboard? Yes, you need a 64-bit CPU to run any 64-bit software, including a 64-bit operating system. Put another way: If you want to run a 64-bit application, you'll first need to install a 64-bit OS such as the 64-bit version of Windows Vista. But the only component that needs to be 64-bit "certified" is the CPU. Your motherboard needs to be compatible with the CPU, but all current-generation motherboards for Intel and AMD CPUs work with 64-bit Intel and AMD processors. To enable all your hardware to work properly, once you get the operating system installed, you'll need 64-bit drivers. If those didn't come with the hardware, you can typically download them from the manufacturer's Web site.   read more »