Are you sure that amazon add the pre orders to their current chart that they display on the website? Bieber was at number 6 on thier charts last night and Cheryl had a similar position last night to what she started on this morning. If pre orders were added surely they both would have risen? From that I would guess that they do not operate their chart in the same way that itunes does by adding the pre orders together on the release day. This would also make sense with the way that they state how may days that each album has been in the top 100. I could be wrong but i really don't get the impression that their positions at the moment include the pre orders (especially with amazon quoting that Cheryl was selling close to double in pre orders)