It turned out to be what I suspected. I moved my root file system to the new drive, removed the old root drive and got the new drive off of IDE2 (one of the Promise RAID channels) and on to IDE0. It seems to be working perfectly with the latest Fedora kernel and the latest nVidia driver. I think something in the Promise area would cause the lockup with DMA turned on on IDE2.
Again, for others who have found no other answers it doesn't hurt to check the seemingly unrelated areas for the source of the problem.