X86_64
This is what Vince was talking about, to expand on it Intel wanted to remove the X86 licence from AMD, AMD were already developing their own set of Extensions, that's AMD64, it was very successful in the server space, to stop Intel withdrawing X86 AMD tagged AMD64 on to X86 for 64Bit Computing on the Desktop, Intel tried to counter AMD64 with their own 64Bit IP but failed. With that AMD forced Intel to licence AMD64, Intel and AMD ended up cross licensing X86 and AMD64. X86_64.
Microsoft use X86_64, Linux which includes server OS's use AMD64.
Edit: Its around about that time Intel really rapped up its illegal shenanigans against AMD.
Also, Games that are available on Windows but also run natively on Linux run far better on Linux than they do on Windows.