The order that fields will appear on the out-of-the-box default SharePoint NewForm.aspx form in response to New, New Item, is governed by the order of the <FieldRef> elements beneath the <ContentType> tag. This wasn't spelled out anywhere that I could find, so this seemed like a good place to document yet another of what I call "What Mother [Microsoft] Never Told You About Controlling The Order Of How Fields Are Rendered In Response To New, New Item" in a custom SharePoint list. :-)