a stub, in 
  case SSE2 is available. This stub is only a simple call and return, which has
  the least possible impact.</p> 
<p class="Body">With this stub however - doing nothing - it is not possible to 
  mix SSE2 optimizations with MMX optimizations (while vice versa is possible).
  This means that all optimizations (especially for 3rd party products using 
  GR32 code) must be available in both MMX and SSE2 flavour. Since both 
  technologies are very similar an update should be fairly possible.</p> 
<