This is an old thread, but I found it under a search of "X-plane" and thought I'd chime in too.

I just bought and set this program up on my 3 GHz PC with 1 GB Ram and ATI top of the line GPU and it runs fine but will not run at the highest resolution and other graphic goodies possible without a pop-up in the program informing me that the performace settings are set too high and automatically being reduced. The reason I am running out of top end is probably due to using a 25 inch LCD monitor placing quite a load on the processor which is an Intel CPU. I hear the AMD CPU's do much better with this GPU card and might just swap over to my AMD PC because of that, not that I need to it runs fast as it is and looks good.

There isn't that much difference in the graphics between the top settings and what I am told by the program I have to live with, when it switches to the lower settings I can't really see the difference except for the occasional short duration little screen lags that I was only occasionally getting before at the extra-high settings no longer occur. I am happy with x-plane, no doubt, its great but I don't have anything else to compare it with because this is my first SIM for flying. I agree with earlier comments in this thread that the flight characteristics are very realistic and the graphics are just fine too... although I have one major complaint, I sure wish they had mapped the world terrain all the way up to 62 deg Lat or even higher instead of cutting it off at 60 degrees Lat. - As it is I can't fly all the way to Anchorage Alaska which is a disappointment with all of the mapping they have provided when buying the full seven DVD disk set. As a minor complaint, although the terrain is correct and the runway placements are right the airports aren't realistic enough. For example for the Wadsworth Muni. airport in Ohio the program has the ramp on the wrong side of the runway. If the creator of this program would release software which would allow pilots to voluntarily correct these errors and then submit them to the developer of this program, over time we would have something much better. Of course, this kind of error makes no real difference but would be nice to have it right.

The 8.4 version of X-plane can be downloaded as a demo but only lasts for six minutes before a pop-up gets in your way inviting you to purchase the program but when flying the UA heavy passanger airliner you can set the autopilot and fly it through the heading and vertical climb rate knobs for as long as you want! So I found a way around that but that was when I was only using my mouse, I didn't try it with the external yoke control which I later purchased when I bought the full program. The program can be purchased as a single DVD disk which only has small map of southern California to fly around in... well, it seems small when I am flying the jets but when I select a Cessna 172 then it goes on and on for a long time. You can also buy the full 7 disk set which covers most of the world, except the far northern and southern latitudes that they figured weren't worth including, grrrrr.

I tried running this program on my 1.6 GHz Centrino notebook with 512 MB of RAM which has an ATI Mobility Radeon 9700 GPU chip in it and the graphics run and look just fine. The program will autoset the graphics to the power of the notebook/GPU but even at reduced settings it seems just fine to me. You can also go into settings and change the resolution, amount of other traffic in the air around you, amount of trees, roads, etc. etc., loads of variables to fine tune it to smoothly run on either slower or top of the line computers.

Here are the published requirements for version 8x:

Windows Pentium 2 ghz+
Macintosh PowerMac G5 1ghz+
Linux x86 2 ghz+
Linux 1ghz+
RAM 384 meg 1 gig for speed
Disk Space 4 to 60 gig (depending upon how many maps are loaded)
3-D CARD OpenGL
VRAM 32 meg
Monitor 1024x768+
Joystick/Yoke USB

X-Plane CD comes with several programs:

Airfoil-Maker (to make airfoils for your aircraft if you would like to make your own planes).
Plane-Maker (to make your own planes and helos if desired)
World-Maker (to make your own scenery to fly in if you like)
Weather-Briefer (to get a weather-briefing before your flight if desired)
X-Plane (the actual flight simulator)

Here is a web page where screen shots can be viewed: http://www.global-scenery.org - Keep in mind that these are at the highest performance settings which require a very fast PC and graphics card to be able to fly them at this kind of resolution. On lower resolutions settings, even for my notebook computer the terrain still looks very good but both the resolution for the buildings and density of other man made structures are reduced quite a bit when using a slower computer which is required to maintain more realistic flight characteristics.

Although the program can be flown with just a keyboard and mouse alone IMO the CH Products yoke with throttle, mixture and prop control is a must to complete the virtual reality of flying this program and can be purchased through Amazon.com right now for 109 dollars SHIPPED. This price is far better than x-planes online offering for this item at $129.00 and another 26 dollars for shipping making a total saving of 46 dollars if you buy from Amazon. The yoke with its many assignable buttons is very nice to have if you are using only one monitor so that you can assign the buttons for a quick glance to the left or right to see out the windows for pattern work. This can also be done with the keyboard but I find it a pain to use the keyboard for this function.

Now if I could just find someone who has made a plug-in file for the Dragonfly homebuilt which is compatible with version 8.4 of X-Plane! I can find older plugins for the Dragonfly canard homebuilt for earlier versions of x-plane but none of them work with this newer version.

Cheers