how to know if ram is competiable? (240/204pin, ___MHz)?

I believe you are referring to the Pavilion g6-1d60us .. if not you can easily go to crucial.com and check for yourself. You want to get SODIMM the smaller RAM as its for a laptop. So you would get the 204 pin at each 4GB for a total of 8 GB ram as indicated below. If you need help purchasing this we can assist with that as well.

Memory Type: DDR3 PC3-10600, DDR3 PC3-8500, DDR3 (non-ECC)

Maximum Memory: 8GB

Slots: 2

Each memory slot can hold DDR3 PC3-10600, DDR3 PC3-8500 with a maximum of 4GB per slot.*

Umm yeah you just need to look up which pin set your motherboard is compatible with... and the limitations of your motherboard as far as clock speed. And what do you mean by "I currently have a 64bit os, so thats not a concern"? What would we be concerned about if you had a 32-bit?

here is a easy way to find out go to http://www.crucial.com/ and click on the system scanner and when its done it will tell you exactly what you have for ram oh and downloading the scanner is safe

Considering your question I would disagree.

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But use the Ram advisor here: http://www.crucial.com/

the best way is to check the specs of your laptop