Check out this awesome simulator. Only in its second beta release yet it looks amazing.
Assetto Corsa is a great example of how a seated simulator can immerse you directly in to a virtual environment. As you look down you will see the hands and legs of a virtual body, but seated in the same position as you. This convinces your brain that you are actually in the simulated environment and adding to an experience that may otherwise costs thousands in training, track and vehicle hire, unless of course you own the car in question, in which case... well done ;).
Here's the home page to find out more www.assettocorsa.net