Every nVidia card before the Geforce8xxx will dither like this in 16-bit color. Even the beloved "best" GeforceFX cards will look like this
As for the best quality dithering (of cards in this era), there isn't any better than PowerVR cards. The way they work is that they always render in 24-bit color and THEN dither the picture to a 16-bit color buffer, and it's a not-very-weird-at-all 4x4 ordered dither matrix you'd see on S3 and 3dfx but without overdrawn blend grottiness (a common problem for the cards that dither on the texture units). A Kyro can handle Deus Ex. Neon 250 i'm not so sure