Hi Hannes,
Looking at your landscape with RHEL 5.6 , Oracle 10g and R3 4.7 with Archiving enabled, while performing upgrade you need to take care of all these dependencies.
Option of client copy will not help you in getting higher version.
For SAP upgrade you need to look for below options
1) Upgrading the OS
2) Upgrading the Database
3) Lookout for dependencies on Archiving storage in case you plan to change the physical server.
Regards,
Deepak Kori