i dunno about that, with that kind of system it might be better to sell as a working unit, and with that you might be able to sell it for 100-200 bucks depending on who you can sell it to. If its not a gaming rig with high end components then parting out doesn't make sense, because the average low end user doesn't want to know how it works they just want it to work.
selling it: craigs list or maybe ebay, or ask around with people you know.