Why not go with:
Code:
newTD = document.createElement('td');
newSel = document.createElement('select');
newSel.name = 'doorbelasting-' + lastid;
newSel.options[0] = document.createElement('option');
newSel.options[0].value = 'Nee';
newSel.options[0].innerHTML = 'Nee';
newSel.options[1] = document.createElement('option');
newSel.options[1].value = 'Ja';
newSel.options[1].innerHTML = 'Ja';
newTD.appendChild(newSel);
This works in all of my test browsers.