Hi Picklesnipe, paul123 and Dark Mantis,
I suppose you have 4Gb of Ram...
What is your graphics card? Weblink about your exact model-brand are appreciated.
I have not infos about your version Windows ( I suppose you have it
) and a type like Window 7 x64 -64bit.
So if you not have Windows Seven, anyway install a SP1, SP2 or SP3 ... on your Windows, if applicable.
But, if your experience are not good with SPx, you have not a Obligation to install it...
(I speak in normaly situation)
If you have a Window... have you installed a Service Pack 1 for Win Seven, by exemple...
Because SP1 It greatly increases the performance in the game.
Normaly... but maybe you have other things to improve.
(Drivers for graphics cards- Update, DirectX 10, defragmented a Hard disk, etc...)
Have you installed Flight Simulator X: Acceleration. Just a question... for the fun... This is a official add-on from Microsoft for FSX
Another idea: Installed Flight Simulator on different Hard Drive than OS System.
Gloup_Gloup