How to find compatible ram for my laptop.

Just search for a ram chip "ram ddr3 1333". Latencies and all really don't matter much in this case, I guess. Get a known brand. For that few extra hundred, you get 5 year (which is pretty much lifetime for a laptop's useable timeframe) warranty.

What do you use your laptop for? Make you need a max of 4 gb before deciding on buying a 2 gb chip.

If you have a bit of extra cash, I would sell this chip off and buy a 2&2Gb ddr3 1600 mhz chip (or 4&4 gb). A 4&4 gb would cost you around the 5k mark for something like Transcend or Kingston.