Dan,
FlightGear (
www.flightgear.org) is a flight simulator built for Linux primarily but also runs on Windows.
If you want FS9 on Linux you are most likely going to end up running FS9 on Windows on Linux. There are a couple of options. VmWare (
www.vmware.com) is an excellent payware package that I use at work to run Linux on Windows but they also have a version that runs Windows on Linux. VmWare is a PC only product because it uses the underlying CPU to execute the guest OS directly whenever it can.
There are some freeware products similar to VmWare but I don't know how far enough along they are in development. One of these products is called plex86.
A freeware option is Bochs (bochs.sourceforge.net). I have run NT on bochs on XP just to try it out. This program emulates the PC instruction set without using the native hardware directly. That means it will be slower that VmWare but on the other hand it doesn't care what the underlying architecture is so you can run Windows on bochs on a Mac, for example. I am in the process of setting up a new PC to dual boot XP and Windows and, if I ever get around to it, I'd like to actually try FS9 on XP on bochs on Linux.
There is also a Linux product called wine that is a more direct approach to running Windows programs on Linux. It provides the Windows API set directly without running the Windows OS. It can run some of the simpler Windows programs but I don't think people have had much success with FS9.
gw
Cessna N7654 ready to copy IFR clearance to KSMF.
Cessna N7654 cleared to KSMURF as filed.