Originally Posted by mumstheword
The only ones i'm sure you can't do is the 3d waves and the very high shader lighting. I think soft particles can't be done without DX10 as well, but I never did a close up comparison.
all you have to have is the console command entered during the game or added to the config file.
Again, referring to this tweak guide, you can see an extensive list of graphics variables that are broken down to their value based on detail level. You can clearly see what the differences are between high and very high settings as well as a more in depth guide on values you can change to take the graphics levels of detail much higher than very high settings would typically give (view distance, foliage draw distance, etc)