ship to same as bill to

i'm trying to right code that if the checkbox is checked then the bill to fields will copy the ship to fields
so i'm using the code: document.registration.sfirstname.value=document.registration.bfirstname.value;
document.registration.slastname.value=document.registration.blastname.value;

this works for text boxes but country is select box -- how can I have this work to copy over the selected field by the country select box?

document.frm.myselectbox.options[document.frm.myselectbox.selectedIndex].value

so i did document.registration.scountry.options[document.registration.bcountry.selectedIndex].value but it doesn't work

document.registration.scountry.options[document.registration.bcountry.selectedIndex].value
It's gotta be the same object.
You might aswell want to declare the object first to simplify your code:

var obj = document.registration.scountry;
var selectedOpt = obj.options[obj.selectedIndex].value;