Firstly - I don't think PIO/UDMA affects SATA devices. For example, on my NVIDIA nForce4 Serial ATA Controller in Device Manager, the channels say "Serial ATA Generation 1 - 1.5G" in the transfer mode box.
I have my DVD writer on my Primary ATA channel and it says transfer mode - DMA if available, current transfer mode: Ultra DMA Mode 4.
I have a DVD-ROM on the Secondary ATA channel and it says transfer mode - DMA if available, current transfer mode: Ultra DMA Mode 5.
These drivers are using the nVidia nForce chipset drivers - is there a manufacturer's own chipset driver set for your motherboard?