pbuffers and depth textures

Does anybody have some advice for implementing projective shadow maps on a  
system with an ATI board?  For a while I've been using pbuffers and  
WGL_NV_render_depth_texture, but of course that isn't available for ATI.   I'm assuming 
I can still setup a pbuffer to render the depth texture into, but  then do I 
do a glCopyTexture to get it from the pbuffer to the actual texture  object?  
Any advice would be appreciated.
 
Thanks,
Damin.