1. A method comprising: providing a Native Client environment for running native client software in a host hardware architecture, wherein host software running on the host hardware architecture is inaccessible to the native client software; receiving guest software to run in a Native Client environment, wherein the guest software is configured to execute at a specified guest hardware architecture and not at the host hardware architecture or within the Native Client environment, and wherein the specified guest hardware architecture is different from that of the host hardware architecture and the Native Client environment; generating, within the Native Client environment, isolated from the host hardware architecture on which the Native Client environment is configured to run, a first set of software representations of hardware used in the host hardware architecture and a second set of software representations of hardware used in the guest hardware architecture; and providing, using emulation software, a binary translation of the guest software into Native Client compatible machine code for execution within the Native Client environment with the native client software and which cannot access the host software running on the host hardware architecture, including creating, within the Native Client environment, isolated from the host hardware architecture on which the Native Client environment is configured to run, a set of virtual registers representing registers used by the guest software when executing at the specified guest hardware architecture, each virtual register being accessible to the binary translation of the guest software from within the Native Client environment via a single instruction, wherein the Native Client environment is configured to execute the Native Client compatible machine code as the binary translation of the guest software into Native Client machine code is provided, and wherein the binary translation of the guest software into Native Client machine code is provided without porting or recompiling the Native Client compatible machine code.