And just to give you some incintive to use a parser, here is some code that uses HTML::TokeParser::Simple. I don't know what you want to do with these div's, but this code will create a two dimensional array where each 'row' is the 'level' found (outermost div's are level 1 - actually index 0 in the array), and the columns are the div id's. This code does not associate the nested div's - in other words, after parsing you will not know that "insideiwant" was actually inside "iwant". That is not particularly hard to do, it's just that this code doesn't do that. ;)

use strict;
use warnings;
use HTML::TokeParser::Simple;
use Data::Dumper;

my $parser = HTML::TokeParser::Simple->new('foo.html');
my $level  = 0;
my @div;

while ( my $token = $parser->get_token ) {
   if ($token->is_start_tag('div')) {
      push @{$div[$level]}, $token->return_attr->{id}; 
      $level++;
   } elsif ($token->is_end_tag('div')) {
      $level--;
   }
}

# print all div's found
for my $row (@div) {
   print "level ", ++$level, " div's:\n";
   print "\t$_\n" for @{$row};
}

# print first outer level div found
print "the first div found had id '", $div[0][0], "'\n";
[download]

When run with your HTML provided, the output is:

level 1 div's:
	iwant
	nowant
level 2 div's:
	insideiwant
the first div found had id 'iwant'

Hope this helps, if it doesn't, then feel free to respond with more questions. :)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)