I built a custom computer and I'm running a ASUS motherboard, with a Nvidia 6800 Ultra video card and a Western Digital 80GB 10,000 RPM hard drive with SATA and it really helps but you won't see the real potiental unless you open up FS9.CFG with notepad and look for this entry:
TEXTURE_BANDWIDTH_MULT=
The default is set to 0 or 60.
I set mine to 400:
TEXTURE_BANDWIDTH_MULT=400
That really makes the graphics load real quick, like if your panning around the aircraft or scenery with the hat switch on a joystick, before it would take up to a second tops to load a square piece such as a water texture.
But with the value set to 400, that increases the data transfer to the video card and it really makes it perform it's best! Those second blocks are no longer seen in my FS9 while panning

The default value is like taking a gallon bucket and emptying like 100 of them into a funnel in a min.
With the increased value, It's like taking a 18 wheeler tanker and emptying alot of them into a even bigger funnel, increased volume at the same time.
As always, back up your default FS9.CFG before making changes
