Form Validatsions

Hi guys

I am using WP Autoresponder plugin for a site that I am setting up for someone. Primarily because they want to collect custom fields when people fill in their news letter subscription form. Which WP Autoresponder plugin handles but the plugin does not do any validations on the form before submitting the data to the database.

Is there a plugin that will handle validations on fields that it did not create?

I have found this tutorial http://wp-relief.com/2010/09/28/add-js-form-validation-to-your-wordpress-plugin/ on adding js form validations and want to know if that is the way to handle form validations or is there any other way?

Thanks in advance for your help
AllanIT