it comes with a single stick of 4GB DDR3-1066
for gaming performance, am I better spending $20 in a second 4GB Stick of 1066 or on 4GB of DDR3-1600?
Basically, will I see enough gaming performance improvement between the 1066 and 1600 to make it worth tossing out the old memory, or am I better with just more memory of the same speed (upping to either 6GB or 8GB of 1066)
just read article about DDR3 comparison
faster ram does not provide any real word performance increase (you can see boost on benchmarks)
faster ram does not provide any gaming performance. theres dozen of articles that tested from cheapest/slowest to top of the line ram on games and results
Considering the slowest RAM is still thousands of times faster than the alternative in the HDD, maybe only hundreds of times if using a SSD, I'd still go with more RAM. The majority of people, even those posting here, will never be able to tell the difference in speed between the two kinds of RAM without the aid of some sort of benchmarking program. However, you WILL notice a difference between RAM and swap and not need a benchmarking program.
AMD's APUs use RAM as VRAM as well. There have been multiple tests run on Toms showing that faster RAM resulted in better FPS. Go for the faster stuff.
EDIT: I just noticed that your laptop of choice has a dedicated GPU/VRAM. So, you'll be less hampered by the speed of the RAM. Personally, I'd still go for the faster stuff. 4GB is usually good enough on a laptop, and upgrading later is pretty easy.
First, looking at the specs, the 4GB it comes with is 2GB + 2GB, so you can't get a 2nd stick anyways, you'd have to swap out both and get 2 x 4GB. Not sure where you get that it comes with a single stick because it states right in the specs on the page you linked that it's 2x2GB.
Second, most laptops don't let you adjust anything in the bios, so I don't think the faster ram would help.