Well, five minutes work and I have updated the product.
Now when PropViewer starts it will check for MMX, SSE and SSE2.

• For older coputers without MMX and SSE (before Athlon XP or Pentium III) nothing can be done.
  PropViewer will display a message and then quit.

• For not so old computers without SSE2 (before Athlon AMD64 or Pentium IV) propViewer will use
    a SSE subroutine with very little difference in speed.

• For new computers that have SSE2 PropViewer will use the SSE2 subroutine.

For whom has old computers and PropViewer refused to run, just download it again from the link above.

And for people that has downloaded and PropViewer is working, you can keep what you have, the new version will not make any difference.

Stupidity also evolves!