dynamic dropdowns wont be able to accomplish this, but it can be done with a little hand coding. By using an onchange event on the elect list, you can pass the product list lable and value to text fields.
here is an example of doing this using a static select list:
php:
<form id="prodForm" name="prodForm" method="post" action="">
<select name="products" id="products" onchange="document.prodForm.prodName.value = document.prodForm.products[document.prodForm.products.selectedIndex].text;document.prodForm.prodPrice.value = document.prodForm.products[document.prodForm.products.selectedIndex].value">
<option value="">--select a product--</option>
<option value="14.99">B.B. King - Live at the Regal</option>
<option value="22.99">The Band - The Last Waltz</option>
<option value="19.99">Alvin Bishop - Let It Flow</option>
<option value="17.99">Dr. John - Gris Gris Gumbo</option>
<option value="15.99">The Paul Butterfield Blues Band</option>
</select>
<br />
<label for="prodName">Product Name:</label>
<input type="text" name="prodName" id="prodName" />
<br />
<label for="prodPrice">Product Price:</label>
<input type="text" name="prodPrice" id="prodPrice" />
</form>
