I have Fsx on an acer T180 system with dual core AMD 2.20 ghz
3 gig ram and a Nvidia Geforce 8800 GTS graphics card.
Vista Home premium
I would of thought that this system would give me good frame rates but I only get between 11 and 18 fps when I have most of the settings high
This sim works much better on an Intel Core Duo system as tiger stated
It also works much better with Windows XP than with Windows Vista.
the Athlon X2 @ 2.2 ghz. is great, but not for FSX.
the only thing I could suggest is make sure you have purged your system of any free bloat garbage that came pre-installed on your Acer.
Get Windows Vista trimmed down to the bare minimum with annoyances, bloat and unnecessary services turned off.
Run it plain (classic style)
Get rid of any unneeded programs in your startup folder.
May help a little... 