I am trying something similar but it always returns the first value in the description field in the cart.
This is the code i applied to the onchange event onchange="document.domains_1_ATC_<?php echo $row_Recordset1["URLID"]; ?>.domains_1_Description_Add.value = document.domains_1_ATC_<?php echo $row_Recordset1["URLID"]; ?>.domains_1_Price_Add[document.domains_1_ATC_<?php echo $row_Recordset1["URLID"]; ?>domains_1_Price_Add.selectedIndex].text"
although it changes the quotes to " in dreamweaver