Question: I would like to add some RAM to my laptop but I have one small problem: I would like to know what is the fastest speed I can put inside it. 

I know from CPU-Z that I use DDR3 RAM:

One piece of RAM is PC3-10700 (667 Mhz) and the other is PC3-8500F (533 Mhz)

I use Acer Travel Mate 5742G if that's relevant. My Chipset is Intel Havendale/Clarkdale Host Bridge.

Answer: 
You laptop will take up to 8GB and the fastest speed it will take is DDR3 PC3-10600 . 
You can buy it here >> <http://www.crucial.com/store/mpartspecs.aspx?mtbpoid=E5A23A8EA5CA7304>
You can put a faster ram, it will just run at a slower speed. I’ve had once some 133MHz SDR sticks running at 100MHz.