Daniel,
Thanks for the input. I was also not surprised by the fact that the oblique epis and the anatomy did not overlay well, but I was surprised by the dramatic nature of the mismatch in terms of location in space of the center of the images. Also, I was surprised that after alignment, the epi and anat appeared to be on top of one another, but both were still off in the corner of the display (see jpg atttached to my original message). I will try 3dWarp by itself and see what that does and also try the -giant_move and -deoblique off options and see what happens.
Lisa