I presume the N93 is functionally equivalent to the N90?
no it is not http://www.forum.nokia.com/main/0,,018-3019,00.html?model=N93
- on this page you have topic: "OpenGL ES 1.1 Plug-in" and there you can read that : " N93 is the first Nokia multimedia computer with HW accelerated 3D graphics/OpenGL ES 1.1 support. " so for sure performance is much better than n90, but i have not seen some benchmarks for n90, if you will make them please post it if you can.
i also tried to find what graphic chip has nokia, but without any succes, anyone know: ati? nvidia? or maybe some nokia's?