Your setup is almost identical to mine, yet I can't get my second (PCI) screen to run any faster than 1-2 frames per second with full motion video, and it generally seems to have very poor 2-D performance: it seems like it's running in PIO mode, with moving windows or repainting my background being very, very slow. Did you do anything special to configure your BIOS? kernel? XFree86? Can you perhaps post your XFree86 config? For that matter, can you try playing a DVD on each of your screens and tell me whether it plays at full speed or not?