After I installed recommended (!) update of NVIDIA nForce 430/410 Serial ATA
Controller yesterday I do not have any devices listed under ATA Channel 0 and
the DMA is not enabled anymore (the checkbox isn't even there). It used to
shows DMA enabled with Ultra DMA Mode 5. What does it mean? Why is my
harddrive not listed there and not showing DMA enabled? What implications
does it have for my computer?

It seems to me that my computer is working slower now. I tried uninstalling
the Channel 0 driver but when it is reinstalled it still doesn't show my hard
drive and DMA isn't enabled. I tried system restore to the point before I did
the upgrade, and the system restore gives me a message that it was
unsuccessful and that some drivers were not returned to that point. Please
help?!