Quote - ThrommArcadia is correct: in Poser 7, this is no longer a user-changeable option. The manual says that tetxure filtering is turned on by default, but I'm seeing blurry textures in my scenes, especially when I compare the same image I rendered in Poser 6.

It may be on by default, but you can now set it on each texture to either "None", "Quality", or "Fast" using the new Filtering option on the Image_Map node.
A "change Filtering setting for all Images in a material" Wacro is probably going to be wanted.