Questions about PS2 consoles

[i am very sux]

Hi, i have been heard that there are 4 type of ps 2 on the market such as ver 1 to 4 now. I am not quite sure what a different bettwen them, ca some body explain what the different for me pls?

[spooky]

The earlier versions had a few tething problems like overheating and sticking cd trays but these and other minor troubles have now been sorted out with the introduction of newer models.

I believe that the newer versions now have 8 screws in the base instead of 10.

(Hope this is correct as im not a PS2 owner!)