If you have problems with OOMS or use heavy scenery like Flytampa and so on you must make the step to DX10 .
It has changed my sim completely from OOMing everytime I try to land to landing anywhere with any scenery after a long flight
I recommend Steves DX10 fixer with Sweetfx , Sweetfx makes it look better adding colour and bloom and HDR
The DX10 fixer will give you Shadows in your virtual cockpit and improve shadowing massively , here are some shots .