I have recently upgraded to FSX+Acceleration and have been having substantial frame rate challenges with many aircraft in the 2d cockpit.  My FSX settings are quite modest, with low autogen, few special effects, no shadows, and low mesh resolution.  Frames are fine in spot view, but when in the 2D cockpit of default aircraft, like the lear 45, as well as the complex aircraft like the Feelthere Legacy or the Feelthere Airbus, I have substantially lower frame rates (single digits).
I have WinXP and an ATI Radeon Xpress 200 series with 256MB ram.

I always expect a frame rate loss with complex aircraft, but is there a difference in how FS9 and FSX process gauges perhaps? The payware cockpit gauges work fine in FS9 but not in FSX, and the default Lear 45 shows little improvement, though the FPS from outside the planes in FSX is still fine. Any ideas?