for Robert Kosek,
i only show the way to render real relief on very slow GPU without any of shaders and bump mapping. i have created this demo on my very slow computer :
Intel (32 bit) 1 Ghz 512 Mb Ram
nVidia Gf MX 440

and on my video board the FPS is 13-20.
and i have tested it on this machine in VMwave ~ 2 FPS

with video board GFfx 6600 > 250fps...

may be VSync is enabled on your board ?