I have noticed a big difference between bringing in a CG2 as a targa and as a tiff. Also, I have not found that the materials get rid of all the details. perhaps try scaling your materials differenetly. Just an idea.

Below is the link to how to bring in a tiff and use the proceduaral command if anyone is interested.
http://cajomi.de/Forum/showthread.php?t=532&page=2

Silverblade33 - Thanks for the link on heightmaps. I missed that one.