My current specs:Core to DUO 2.93Nvidia 9500 1GB8GB RAMWin 7 64I run FS9 with all sliders to the right, 100% AI and nhancer profile: AA multi 32x with good results however if I change the AA to combined 8s I get low fps with overcast.Should I upgrade my CPU to Quad core? or is it the maximum I can get form FS9? Because I heard that FS9 doesn't utilize multiple CPUs.And how about FSX? Will the CPU upgrade make a difference?

Your problemseems to be graphics related so I'd go for a stronger graphics card. I recommend minimum nvidia GTX260

Oh, OK. Thanks for the advice.