Intel was quick to point out that the ARM version of Windows 8 won't have any backwards compatibility—"Our competitors will not be running legacy applications. Not now. Not ever." But the ol' friendly x86 version? You betcha!
Windows 8 on x86 chips will "Run all of [your] old applications, all of [your] old files—there'll be no issue." This isn't altogether that surprising, you can hear the slightest bit of fear in Intel's voice over Windows breaking free from the x86 pen. [The Register]