Specifically read the section entitled "RISC and x86".
EDIT: In short, programs written and compiled for x86 (everything you've ever run - unless you're in software development and have dealt with Solaris SPARC or similar) do not work on RISC processors. It's possible that if they're written in C/C++ you could compile them for RISC but first someone is going to have to compile/produce a version of Windows for RISC first.