I'll back up the previous recommendation for X-plane. It can run in Windoze, Linux and Mac. They have just released a new version so copies of Version 8, which is still better than MS sim, can be had for US$29. Add any USB joystick and you will have a top notch sim for under AU$100.
Download a demo for free:
http://www.x-plane.com/demo.html
System requirements:
http://www.x-plane.com/sysreq.html
Current prices and deals:
http://store.x-plane.com/cart.php?m=product_list&c=3
There is a huge amount of free add ons for x-plane, and most are free. Checkout
www.x-plane.org for forums and freebies.