There really needs to be a footnote on the chartz for comparing PS2 and PS3

[TWRoO]

Perhaps on this graph for instance:
http://vgchartz.com/hwlaunch.php?cons1=Wii&reg1=All&cons2=PS3&reg2=All&cons3=PS2&reg3=All&weeks=110

there can be small (colour matching to the line) vertical lines in specific places which when highlighted gve more information than the usual exact sales figure.

So at the blip of the PS3 PAL launch would be a line, and when you point over it a small box comes up explaining it. and similar points could be on each week ending in early January.