viziblr

And thanks to the following page (pretty pictures!) I know I should turn it on when I play games:

http://www.codinghorror.com/blog/archives/000484.html

From the article:

"In my opinion, anisotropic filtering is the most important single image quality setting available on today's 3D hardware"

And a link to wikipedia for some more information

http://en.wikipedia.org/wiki/Anisotropic_filtering