Depends on version of IE. Yes, IE7 (and I think IE8) require that you append to the <tbody>.
But you know, if you would JUST LISTEN to Felgall and me you would learn that using createElement() and appendChild() for <tr> and <td> are *NOT RECOMMENDED*!!!!
Using insertRow() and insertCell() will:
(a) Be easier to code.
(b) Work in all browsers (yes, without needed to use the <tbody>).
(c) Execute just a bit faster.
WHY would you WANT to continue to use appendChild() for <tr> and <td>????
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.