Thought that I would pass on a few comments about FSX, now that it has been installed for a few months. Might give others some hope/encouragement.......
Lots of problems initially after installing, and lots of tweaking needed, although this was basically just a matter of following the advice of others (thanks for posting!!) and downloading the various articles designed to improve frame rates. Some resizing of tree/building textures, and lots of experimenting. At one stage I was VERY near to uninstalling FSX and going back to FS9, but perserverance paid, and things DID get better. Main problem was poor frame rates, but SP1 and SP2 seemed to have helped, along with the tweaks. I can now spend less time tweaking, and more time flying, which is what it is about.
Better was to come, with some very impressive add-ons for FSX. It was very interesting to go back to FS9 and try to fly the same flights there. Now FS9 looks very basic in comparison. FSX is far from perfect, and will still need improving, but it IS much better than FS9. The good news for everybody is that the learning curve is much shorter than for FS9, as many of the principles are the same for FSX and FS9, so it has taken me much less time to get FSX working well than it did for FS9. I now ENJOY FSX, rather than constantly being disappointed/frustrated with it. As an example, yesterday I watched a windsock blowing gently in the wind whilst taxying, a small realism detail that gives FSX a great advantage. FS9 was not 'as real as it gets'. FS9 was not perfect when it came out, and it relied on external companies to improve the basic microsoft product, and it is the same with FSX.
So to others who might be having major problems with FSX, the advice is do not give up. There is light at the end of the tunnel. Keep tweaking and it will get better.
Smooth landings. (in FSX)
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And it works for all combinations of XP/Vista and FSX/FS9.
, and a steady hand
and then the program kicks into a continual loop of defragging to free up memory as it's below his target level... I'm sure that is doing wonders for his performance 
