How to replace strings in a file from a list?

[zBernie]

I'm trying replace names in a file, with names from a list included in __DATA__ in the script
below. Now assume I have a text file which contains hundreds of
different names, and I want to replace certain ones with a mapping of say:
JOE -> JOHN
FRED -> FREDERICK
SAM -> SAMANTHA

Do I need to create a hash with the 6 names above before I can replace instances of
JOE, FRED, and SAM, in a text file?

#!/usr/bin/perl -w

use strict;

if ($#ARGV < 0) {
  print "\nUsage: $0 <File>\n\n";
  exit 0;
}

my $userlist = qq{$ARGV[0]};

open(FILE, qq{$userlist}) or die("$!: $userlist");
my @users = <FILE>;
close(FILE);

while ( <DATA> ) {
  print $_;
} 

__DATA__
JOE
FRED
SAM