My 2 cents...

My machine:

AMD Athlon64 +3300
2GB RAM
BFG 6800GT
NVidia drivers 91.33
OS: WinXP Pro SP2

Settings:

Shader Version 2
Resolution: 1280x1024
AA: x2
Texture Filtering: AFx4
Unit Detail: Highest
Effects Detail: Highest
Building, Vegetation, Grass and Texture detail: High
Shadow Quality: None
Bloom: On
Reflections: On

Tutorial and both battles where as smooth as silk...

Going to play with the shadows a bit more...