Is VGCharts accurate or not?

[FishyJoe]

http://vgchartz.com/japweekly.php 

SteveSmith said:

Gran Turismo 5 Prologue 102,963 number is only the retail disks. The game can also be downloaded. So the real number is probably around 300 000.

You sure have balls to question the accuracy of this site when you make a statement like this.