if your running dx7a dont bother with dx 8 untill some games and drivers are out that properly support it i installed dx 8 on my win ME box and lost a few fps and a hundred or so 3d marks, not that i really care my games still play smoothly and i see better 32 bit color output under 3d. If your into image quality i think they mah have improved it a bit over 7.0 but it looks like you pay the price with a *slight* preformance decrease.
This is with my v7100 mx card with 6.34 drivers, the 7.17's are horendous quality wasnt helped and preformance was trashed