How to use ATI_draw_buffers?

I would like to use ATI_draw_buffers to allow my fragment programs to output some additional data for post-processing purposes.
The problem is that when I try to set up additional buffers with glDrawBuffersATI() (for example: GL_BACK as first buffer, GL_FRONT_LEFT as second and GL_FRONT_RIGHT as third), the binding stays the same as before call to glDrawBuffersATI() (that is: GL_BACK, GL_NONE, …).
I have read somewhere that Win32 doesn’t support stereo-buffering so maybe that’s my bad. But how should I use this extension then?
When I query the number of AUX buffers, I get 0 as result.
If any one could give me an example on how to use this extension, I would be very grateful.

By the way: I use wxWidgets as windowing system for my OpenGL application and ATI Radeon 9700 as hardware.