First of all your going to need a Xbox to put the pc into. Just open all of the screws from the bottom of the xbox and pull the top up from the console. Once the top is off, pull out the stuff from the inside including the metal frame.
Step 2: Power Button
If you want to use the Xbox original on/off button, dvd disk opening button and the leds for the power on and the hdd youl have to modificate the Xbox button circuit. This includes some soldering but nothing too hard. First of all you need some wires for the two leds (each on the othed sides of the circuit.) the power and dvd opening button. The each led in the Xbox have two colors Green and Red. You can choose wich one you like. i decided to use green light for the power and red to the hdd. Just solder wires to the leds and for the power and dvd button. If you don't know how the buttons work use a multimeter to work that out.
Once you have solderd the wires to the circuit youl have to cut the copper from the black side of the circuit to make it work. just follow the red lines in the last picture and make sure that it wont lead between the cuts anymore. if you don't do this the buttons wont work.
Step 3: The Computer
1.Its cheap (for about 50 Euros)
2. It has got low power intecrated prosessor: Intel atom 1.6Ghz dual core (which is otherwise a surprisingly effective)
3.it supports DDR2 Ram
4.it has got intecrated Graphic card (64 Mb)
Now you have two choices. Build the computer straight inside the Xbox or build it on to table or something and play with it a little and install the hackintosh right away. i choose to build it on the table and install OSX right a way.
Step 4: Installing OSX Leobard - to Snow Leobard
Step 5: Putting Everything to Its Own Place
Now for the tricy part. Try to get all inside Xbox. First of all you have to choose the order of things inside. i choose to put the motherboard to the right end of the chasis and psu to the left side. On top of psu i put the dvd drive because its just on the same height like the original xbox dvd drive. And put the HD somewhere it fits. Cut to the back of the xbox holes for the psu cord and for the mother board I/0 panel. Screw the motherboard and psu to the chasis whit small screws and tape or glue or something to get the DVD drive to hold in place. Put the top of the chasis back to its original place and put the screws back.
Step 6: And Its Ready.
Have fun with it.