This will decode the licence keys from your registry for Windows and Office

Doesn't work for me on Windows Vista 64 - sub decodekey returns BBBBB-BBBBB-BBBBB-BBBBB-BBBBB, though I was hoping to see my Windows product key.

Same thing with the other script referred to by Burak.

Mind you, some of the Win32API::Registry and Win32::TieRegistry tests failed (which I haven't investigated). Maybe that's part of the problem.
Have you successfully run that code on Vista ?

Cheers,
Rob

UPDATE: Probably should provide the complete code I ran:

use strict;
use Win32::TieRegistry;

print decodekey(qq!HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows NT
+\\CurrentVersion\\DigitalProductId!), "\n";

sub decodekey {
  my @digits = ('B','C','D','F','G','H','J','K','M','P','Q','R','T','V
+','W','X','Y','2','3','4','6','7','8','9');
  return "No key found\n" if ($_[0] eq "");
  my @id = split(/,/,shift);
  my $key="";
  for (my $i=28; $i>=0; $i--) {
    if (($i+1)%6) {
      my $ac=0;
      for (my $j=66; $j>=52; $j--) {
        $ac<<=8;
        $ac+=hex $id[$j];
        $id[$j]=sprintf("%x",($ac/24)&255);
        $ac%=24;
      }
      $key=$digits[$ac].$key;
    } else {
      $key='-'.$key;
    }
  }
  return $key;
}
[download]

UPDATE: Don't worry - my script is obviously crap. No warnings, doesn't actually make any use of Win32::TieRegistry ... and I don't feel disposed to fixing it.