You can enhance your Flight Simulator hobby by creating an environment that closely mimics an aircraft cockpit. You don't need to go all out with expensive hardware to build a rig that will make you feel 'right there'
Most video cards support two monitors. You can pick up a cheap PCI video card to supplement your current one, thus having access to up to four monitors. Then buy a couple of smaller monitors (7",or 9" or 12" ) where you will display your instruments. Microsoft Flight Simulator X (FSX) allows panels to be displayed on different monitors. Keep your main monitor for displaying only the outside graphics.
Arrange your setup in a manner similar to an aircraft cockpit. The small isntrument panel monitors should be under the main, outside view, monitor. In the picture you can see that I built an enclosure for a small 9" LCD display from the shell of an old computer.
Buy an USB keyboard and/or a gaming keyboard and assign flight simulator commands to it, then label the keys. You can go all out and print nice graphics to make it look like aircraft switches.
One item you shouldn't skimp on is quality rudder pedals and joystick/throttle combo (or yoke/throttle).
You can cover your panel monitors with a bezel in the shape of an aircraft instrument panel made from quality cardboard with holes cut in for instruments.