A lot of people have been trying to munge html with regexes lately. HTML::Filter gives you a lot more power. I like using something like this, sweeten to taste:

package MyFilter;
use HTML::Filter;
use vars qw( @ISA );
@ISA = qw( HTML::Filter );
sub start {
  my ($self, $tag, $attrs, $attrseq, $origtext) = @_;
  my $rewrite;
  if (exists $attrs->{src}) {
    $attrs->{src} = "http://foo.bar.com/$attrs->{src}";
    $rewrite = 1;
  }
  if (exists $attrs->{href}) {
    $attrs->{href} = "http://foo.bar.com/$attrs->{href}";
    $rewrite = 1;
  }
  if ($rewrite) { 
    print "<$tag";
    foreach my $attr (@$attrseq) {
      print qq[ $attr="$attrs->{$attr}"];
    }
    print ">"; 
  }
  else { print $origtext }
}
package main;
my $filter = MyFilter->new();
$filter->parse($html);
$filter->eof();
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