Upgrade of APO - Dependancies??

Dear all,

We are currently using APO version 3.10, BW version 3.10 and R/3 version 4.6c. We are looking to upgrade all, but were considering APO and BW first. If we were to upgrade to SCM5.0 and SAP NetWeaver 7.1 are there any technical/application implications if we do not upgrade R/3 at the same time?

Any help would be appreciated.

Thank you