Well, if you're going to use File::Find, you might as well use the saner syntax of File::Find::Rule.

#!/usr/bin/perl 
use warnings;
use strict;
use File::Find::Rule;

my $dir = "C:/Windows";

my @files = File::Find::Rule
    ->file()
    ->name('*.txt')
    ->mindepth(1)
    ->maxdepth(1)
    ->in($dir);

print "$_\n" for @files;
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For a job this simple, though, I would probably use glob().