Pretty easy. Any PC core 2 class with USB port and headphone jack will do. I have winds 7 installed on mine. I picked up an LCD from goodwill for $25 and decased and mounted it. For audio you can go the audio route I outlined in the CCC software thread. I'd use a smart power strip to handle the PC and perhaps install a push button for power in the front if the cabinet somewhere.
For the PC, there are tons on eBay that work for around $175.00 shipped.