Check in the bios first. Somewhere you should see a place to enable or disable DMA on the Primary and Secondary IDE channel. In My bios, there's also a section to set each device for UDMA 33, 66, 100, or off. Make sure that's either set to AUTO, or to 33 i beleive is what it wants. Once you are sure that the bios settings are correct, restart windows... (I'm making some assumptions here, but more than likely they're correct.) Go to the device manager and check that DMA is enabld under IDE controllers. DMA can be enabled or disabled for each device on each channel.
Another note... these drives, I've been told, pretty well INSIST on being set to master. That being the case, if your machine is like 99% of machines today, you'll want the writer set as master on the secondary controller. If you're putting it on the controller with another device, make sure the other is properly set to slave setting. Also, do NOT use "cable Select." As I understand it, these drives don't like to be set up cs either.
Let us know how you make out!