With STYX you can turn on anisotropic filtering. ^^
Click Demo
Don't know any free alternatives.
There's also a basic command included in DBPro:
Quote: "SET OBJECT FILTER
This command will set the texture filtering mode of the specified object. The Filter value sets the texture filtering, which controls the smoothing effect of the texture as it is mapped to the object. A Filter value of zero does no mipmapping, a value of one uses no smoothing and a value of two uses Linear Filtering.
Syntax
SET OBJECT FILTER Object Number, Flag
SET OBJECT FILTER Object Number, Stage Number, Flag"
/edit: Oh, you can of course also turn it on in the Driver Menu (at least in Nvidia Control Panel).