Laptop RAM upgrade (stick with the same type or go faster)

[demonix]

I had decided a while ago to upgrade the RAM in my laptop since only having 2GB doesn't really cut it with what I'm doing now (along with the fact that 256MB is allocated to the GPU), but I wasn't too sure what to do and now that I'm going to be going ahead with this part of the upgrade in the near future I want to get all of my issues sorted before I purchase anything.

The laptop has pc3-8500 (1066MHz) RAM, but when I checked with the crucial advisor at the time it suggested pc3-10600 RAM and now it's suggesting pc3-12800 RAM.

So the question is can I use faster RAM like the crucial advisor has suggested, or should I stick with the same type that is already used in it?

The laptop in question is an Acer Aspire 5551

 

[demonix]

It didn't suggest pc3-14900 or pc3-17066, so it's likely that pc3-12800 is the fastest it can support but I was either going to stick with pc3-8500 (having two modules instead of just one would most likely speed things up) or go up to pc3-10600 depending on how trustworthy the information provided by the advisor on the crucial is.