Well like many people i upgraded from the original xbox as a media centre to raspberry pi. I was using a punnet style case but there were too many wires on show so i used my old case.
Here is the cheapest case and media centre poor people could have.
xbox case - free
ide hdd - free as i already had one in my xbox
xbox ir remote - free
belkin 7 port usb hub - £10
ide to usb with power supply - £10
2 x usb extension cable - £2