See Simpler than XML::Simple for some reasons why you should not use XML::Simple and what to use instead.

As we do not know what do you need the data for, I can only guess in what format would you like them so just a tiny example. This code specifies that form each &lve;Vendor> you want the vendorUniqueKey as the key and the name as the value and then lets you execute some code to process this data once the </Vendors> tag is parsed. This style lets you process huge files without keeping everything in memory.

use strict;
use XML::Rules;

my $parser = XML::Rules->new(
    stripspaces => 7,
    rules => {
        Vendor => sub {return $_[1]->{vendorUniqueKey} => $_[1]->{name
+}},
        Vendors => sub {
            my ($tag, $vendors) = @_;

            print "We have " . scalar(keys %$vendors) . " vendors\n";
            foreach (keys %$vendors) {
                print " $_ => $vendors->{$_}\n";
            }
            return;
        },
        ':default:' => ''
    }
);

$parser->parse(\*DATA);

__DATA__
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Import format="3.0" fileId="54630000-3141-1404-4310-7F0000014030" fil
+eCreationDateTime="2+012-07-23T06:04:31.415" catalogSource="TLCMz">
    <Catalog>
        <Vendors>
          <Vendor name="Allen Systems" vendorUniqueKey="ALLENGRP"/>
          <Vendor name="Aonix North America" vendorUniqueKey="AONIX"/>
          <Vendor name="Beta Systems Software" vendorUniqueKey="BETASY
+S"/>
          <Vendor name="BMC Software" vendorUniqueKey="BMC"/>
        </Vendors>
    </Catalog>
</Import>
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