How about:

use strict;
use File::Find;

my(@directories_to_seach);

@directories_to_seach = "C:/Documents and Settings/Desktop";

find(\&wanted, @directories_to_seach);
 sub wanted {
  if ("$_" =~ /^AB\sDAT*\.doc$/i) {
   print "$_\n";
  }
 }
[download]