How do I determine which type of RAM my laptop uses?

Check out wikipedia:
http://en.wikipedia.org/wiki/File:Laptop_SODIMM_DDR_Memory_Comparison_V2.svg

Then count the pins next to the notch to confirm that it is DDR2.
(Or check your picture. Enlarged it is easier to count and there are 20 pins before the notch).

Also useful to known: PC6400 aka DDR2-800 runs at 400 MHz (which explains your CPU-Z value)