Ive slowly improved as well. I downloaded directx 9 today and it helped. I also have been trying to clean up my processes and Glary Utilities did help.
I went from 800 x 600 with the 1?? texture size with only detailed terrain selected back to 1024 x 768 with detailed terrain, water, and bump map selected.
I have disabled other plane skins and I took the x outta the horizon box.
My frame rates are slower, but I dont notice it as the stuttering has slowed down.

Heres my system (DELL)
OptiPlex GX260
General
Family Name OptiPlex
Family Model GX260
Windows Version Microsoft Windows 2000 Professional
BIOS
Version A03
Vendor Dell Computer Corporation
Date 2002-09-24
Processor
Model Intel(R) Pentium(R) 4 CPU 2.00GHz
Speed 2 Ghz
Hard Drive
Drive Size Free Space Utilized
C: 7 Gb 2.32 Gb 67 %
D: 11.64 Gb 9.01 Gb 23 %
CD/Optical Drives
Drive Type
E: HL-DT-ST DVD-ROM GDR8163B
Sound Card
Model Unimodem Full-Duplex Audio Device
Card Slots
Slot ID Designation Usage
System Slot 0 PCI1 Available
System Slot 1 PCI2 Available
System Slot 2 PCI3 Available
System Slot 3 PCI4 Available
System Slot 4 AGP1 In use
USB Controlers
Name Version
Standard Universal PCI to USB Host Controller USB
Standard Universal PCI to USB Host Controller USB
Standard Universal PCI to USB Host Controller USB
Intel (r) 82801DB/DBM USB Enhanced Host Controller USB2
Video Adapters
Model Memory
NVIDIA GeForce 7600 GS 512 Mb
Memory
Slot Size Speed Type
Slot 1 1024 Mb 266 Mhz SDRAM
Slot 2 1024 Mb 266 Mhz SDRAM
Available Slots 0