Hae a look at FMS (Flight Model Simulator), it is available for free, and there are a couple of vendors selling the FMS Interfaces.

Follow the FMS link on my [link=http://myweb.absa.co.za/eric.brouwer/index.htm]homepage[/link], and have a look at my [link=http://myweb.absa.co.za/eric.brouwer/interface.htm]Interface Vendor links.[/link]