Make the input form simpler

Hi
I want to make the input form simpler - in particular I want to turn OFF the field "Description:" - which I think is part of the content type. When I go to edit the Ad content type and put blank in the Description Fields I still get a description field on the input form. Is this field needed? How can I get rid of it?

I'm having problems because the two major input fields "description" (which I don't want) and "ad body" (which I do want) are appearing at different input field sizes in different browsers. So, in Firefox the "ad body" field is larger and attracts attention - which is OK. But in IE the Description field is largest (very large) and attracts attention.

Is this a styling issue? Or can I turn the description field off entirely?
thanks in advance
Debs