I'm not sure I understand what you mean by that.  What are "april drivers for poser"?

This is what I installed from the ATI website:
ATI Catalyst 8.3 Display Driver for Windows XP Professional/Home Edition

Is there something else I'm supposed to install specifically for Poser?

"You don't know what we can see
Why don't you tell your dreams to me
Fantasy will set you free." - Steppenwolf