NetWeaver architecture vs. Websphere architecture

Does anyone know of any comparisons between these two architectures... i.e. XI, workflow, Portal, etc..?

We have been asked to come up with a Position Paper for SAP NetWeaver technologies as the client is currently thinking that the whole websphere suite is the way to go... Unfortanetly the service.sap.com website doesn't really have any good info (that we can find).

Am I wrong in saying that if you are planning to continue to use SAP then you will have NetWeaver anyway as all SAP's future developments are based on it?

And what about integrating websphere with SAP - I've been told that you will need XI to enable this anyway?

Thankyou,

Jason.