But that's beside the point, what is important is that the entire lineup has room for dual hard drives but most of them only ship with a single drive--an almost unforgivable waste of precious space in a laptop. It can also accommodate up to 16GB of RAM but sometimes come with much less. Both of these problems can of course be amended!
Unfortunately the ASUS G53 is unusually difficult to upgrade. Underneath the laptop, where you usually find a plastic cover that you can open up by loosening a few screws to upgrade HDD and RAM, there are no screws to be found. Instead you have to access the internal components by removing both keyboard, touch pad and palm rest; only then can you loosen the plastic cover to access the hardware.
Here are the steps on how to do this, but as always you do it at your own risk! If you have no prior experience with electronics or feel uncomfortable with the procedure, just leave it alone and take it to a professional. It is also advisable to use an anti-static wrist strap when working with RAM modules and other sensitive parts.
That said, it's not brain surgery. What you need is a Phillips- and a flat-head screwdriver (size small) and of course the parts you intend to insert or replace--in this case a hard drive or SSD and/or DDR3 SO-DIMM RAM.