Encoding URLs yourself can be a pain. Check out the URI::URL module, it does a great job of encoding URLs and it plays nicely with LWP...

use LWP::UserAgent;
use URI::URL;

my $WWWAgent = new LWP::UserAgent();
my $site=new URI::URL 'http://somecompany.com/srcipt.dll';
$site->query_form(
        text      =>      'some text');
my $WWWRequest = new HTTP::Request 'GET', $site->as_string() ;
my $WWWResult = $WWWAgent->request($WWWRequest);
die "Error submitting form $WWWResult->code $WWWResult->message" 
        if(!$WWWResult->is_success);
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The HTML::Parser module provides an excelent framework form parsing web pages and it works well for parsing the documents returned by LWP.