Write a Perl script activated with cron visiting a webpage?

I would like to know how to write a perlscript visiting a website. Not by fetch but as a 'nobody' retrieving the HTML-page (http). For example to check for changes on that page.
tnxs :0) jochum

#grab.pl####################################
#!/usr/local/bin/perl
$local_dir = "/tmp/grabbed_data";
$target_file = "http://hoth.stsci.edu/man/man1/crontab.html";
use LWP::Simple;
getstore("$target_file","$local_dir/crontab.html");
#comment out the following line to run via command line
print "Content-type: text/htmlnn";
print "DONE!";
############################################
if Simple.pm not found, get it from http://www.linpro.no/lwp/libwww-perl-5.48.tar.gz
To run from command line:
perl /path/to/grab.pl

Go to the target_file's URL to find out more about crontab.