I assume you do know that x86 is the 32Bit CPU architecture used in standard PC processors, and x64 is the 64Bit version of this. If unsure, install the 32Bit version as it will still run. Knowing if your PC is 23/64Bit is really quite simple, My Computer > System Properties. It says the system type as: 64-bit Operating System. For the standard consumer, this is really not much of an issue that affects how they work.
Though, personally I don't find Linux harder to use than Windows, many people would still.