The version for Joomla! 1.7 was completely rewritten. But it not so difficult to adjust the script for your template. Look into the source code and adjust the search string in the file easycalccheckplus.php. If you need help, post the link to the site.
funny. where is the com_users folder for when I can delete it without loosing (almost) anything? What changed is that when you don't type all (required) fields and you click send nothing happens (otherwise there comes an error message). I'll install it on my official website.