Box for Playing Media with VLC

[nauen]

Hello people

i want create a machine for playing all music and video stuff.
i have two media clients they cannot play some files so i have enough for the buggys.
I thing only vlc can help me.
i want a machine with low power consumption but can play everything without HD stuff.

what i need to buy and which OS is the best for this solution.
It have to boot fast so i go to the station in the morning turning on, select my music and take a shower...

The other problem ist the space... should i save the stuff in the box? Or in nas? i have 500GB and counting... i thing a nas need more power as a big storage in box...