The RAM seems to be compatible with the laptop, from what I've searched, but you can't mix the RAM with the RAM already in your laptop, you will need to take it out first.
The RAM here, from the same store would be suitable for your laptop, but remember to take the old RAM out: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
It really needs to be the same speed and timings. The RAM you chose is DDR3 1066 at 7-7-7-20, so if what you already have matches that, then you should be ok. It's always best to have a matched set, though because there can be problems with unmatched RAM.
And just one more thing, there will probably only be one setting for speed and latency in the BIOS, not one for each individual module, so just make sure that the latency is CL9, and all should be well.