That's weird.  As far as I know, from other forums and the help I've received from this forum is that Windows 7 x64 is suppose to be the best and most stable OS for use with FSX.  I'm using Win 7 Ultimate and FSX runs perfect.  I'm assuming there shouldn't be that much difference between Ultimate and Pro, which is the one you're running.

Did you re-install the drivers for your graphics card and update the new OS?

Also, try opening up your Task Manager after opening FSX and set the priority to HIGH.

Hi Jim,
You can find it by typing "task manager" in the search box when you click "Start".  Make sure FSX is already running.  I do it after the FSX main menu loads up.

Click on processes and look for FSX.exe.  Right click on it and scroll to "priority".  By default my system sets FSX priority to "normal".  I change this to "High".

I *think* it should improve performance even if you don't have other apps running because the priority is changed from "normal" to "high".  I don't use "Realtime" (suppose to be the fastest) because I hear it's not that stable.  Someone please correct me if I'm wrong.

You will have to do this everytime you start FSX because everytime you exit fsx, it resets.

I run 3 apps when using FSX.  I have FSX, UT2 and the saitek panel app running.  I just set fsx on high and leave the other 2 alone (normal by default).

It's one of those "try and see" thing.  Some people get improved performance while others don't.

Here's a step by step guide... http://www.sevenforums.com/tutorials/83361-priority-level-set-applications-proce...