Can't run PyQt apps with MacPython

[Morad]

I recently got a new MacBook Pro with Leopard, and would like to
develop using Python and PyQt. I installed the latest Qt SDK, updated
MacPython to V 2.5.4 and then proceeded to install SIP and PyQt as
described in Mark Summerfield's book on PyQt Programming. Everything
went fine and none of the scripts complained. However when I want to
run a demo app, I get the error message "Fatal Python error:
Interpreter not initialized (version mismatch?) / Abort Trap". Anybody
can help?