In Battlefield Vietnam we played a short sequence on the map "Ho-Chi-Min Trail" and determined the frame rate using FRAPS. All quality settings were set to maximum through the Options->Video menu.
NVIDIA's drivers also have some trouble in Battlefield Vietnam. Although there weren't any rendering errors, the performance of the NVIDIA cards is disproportionately low compared to the X800 XT. Or, from the other perspective, the X800's performance is disproportionately high.