Direct transfer Depth Buffer to texture

Is there any quick method direct transfer Depth information into on texture without read back to main memory?

glCopyTexSubImage2D() with an internal format of GL_DEPTH_COMPONENT

I try to use pbufer and directly bind the pbuffer to a texture.
For RGB it works.
wglBindTexImageARB( pbuffer.hpbuffer, WGL_FRONT_LEFT_ARB )

however, when I use WGL_DEPTH_COMPONENT_NV
it fails.

Now I get it right

add WGL_BIND_TO_TEXTURE_DEPTH_NV, TRUE,
for the pixel format
and WGL_DEPTH_TEXTURE_FORMAT_NV, WGL_TEXTURE_DEPTH_COMPONENT_NV,
for the pbuffer attib

what’s the best way to do this on ati boards? use gl_arb_depth_texture somehow?