Drupal Commerce Adding fields to Add To Cart page I need some suggestion to add some fields to the "Add to cart" page.

Out of many products, one of the product requires some user information to be filled before proceeding to "Add to cart" process. I am selling a product of type "Exam". Before buying Product of type "Exam" (Before adding to cart), user has to input his person details like name, address, DOB and other mandatory details without which he is not able to proceed.

Could you please guide me, how to achieve this?

Update:

Shall I use Product Attribute fields to capture user inputs over product display page? As this information is not associated with the Product, but with the order and need to be captured before Add to Cart button is clicked.
Thanks all of you for your valuable time and suggestions. More or less all suggestions 'll be required in near future. I have up-voted all of you for your help. However on other side I got the answer, what I was looking for. 


  It sounds like you need the Customizable Products module.
  
  Once you have that module installed, you can go to Administration > Store > Configuration > Line item types. Add a custom line type and add as many custom fields there as you'd like. You'll see - the
  interface for adding fields to the custom line type is the same as
  when you create a content type, so it's easy to use.
  
  Then, when you've added all the customer info you need in your new line item, go ahead and modify your 'Exam' product to include
  those fields in the product display. Hit the 'Display' settings for
  the content type, and configure the settings for the 'Add to cart'
  field. Make sure you choose the correct line item for it to use and
  Save!
  
  Helpfull screencast could be found at http://vimeo.com/36106455