hey man, whatever floats your boat
. There's tutorials on youtube and everywhere for ssd's and hdd in optical bay adapters if you ever decide to do that.
I run several VM's on the latop, so 8gb is a necessity for me. It definitely isn't necessary for most people. Since it uses shared memory, if you had 8gb there would still be 4+ gb left to the system after alotting 1 - 1.5 to the GPU, and windows grabbing its share.
....but even bone stock, it's amazing for it's price.
It'll easily handle TF2.