I have an ide hp 8x4x32x (a rebranded yamaha?) and, even tho hp says - i think - to disable dma, I found myself unable to record listenable audio cd's (data was okay) from the hdd with dma disabled - a few tracks in it would start sounding like it was skipping. Once I re-enabled dma, I've had no probs since.
Best bet is to enable it if you can, and only disable it if you have problems.
* Mileage on this advice will vary!