Electronics Xbox360 Scratch Build Electrical Help Please

Okay, hello again everyone.

What im doing is building a xbox 360 case from scratch, i've already started ordering parts and will post a project log soon.

ANYHOOOOO.... my problem.....

after some research and help from Zurechial, Atheistmunk and addicusSD (thanks again guys!) i know how to add a molex onto the 360 motherboard and get power feeds from other places on the motherboard...
BUT... if i was to use for instance the 12v supply from this picture



then create a circuit in series that runs 4 leds that are 3volts each and are 20mA with resistors and all but thats not really important for what i want to know i think

like so....



THEN

could i branch another similar circuit from this supply?

like so....



Or am i being a complete tool?
oooooorrr should i just run many led's in a parrelel circuit?

please keep in mind i am no pro when it comes to electronics but am trying to learn

so if anybody could correct me, come up with a better way to do this or can draw me the right electrical diagram then please let me know thank you!