Cascading/Chained Dropdown boxes

Hi All,

I’m trying to put together a contact form for a website I’m building – I have been using Contact Form 7, but because things have become a little more complicated I am now needing a system where the user can select a reason why they are contacting, which will then produce another drop down box for further information.

Example

1st box will have the options:

[General]
[Feedback]
[Consultancy]
[Course Information]
[Event Information]

If selected [general], [feedback] or [consultancy] it won’t add anything else to the contact form, but if you choose [Course Information] it will provide another drop down box for [Health & Safety] and [Manual Handling], choosing one of these will then show another drop down box populated from the appropriate table within the database.

My question is, are there any plug-ins that can help to achieve this? Or am I on my own and will have to try and put something together either with JavaScript/php or ajax/php?

Does anyone have any experience?

Thanks