Hi Andrew
Yes, SAP NW7.02 Not supported in Windows 2008 R2 Core server, because in windows 2008 R 2 core supports Virtual machine(VM), On virtual environments you can install the NW 7.02 SAP system with Windows 2008/2003 enterprise server version (Not on Core)
Kindly refer the SAP PAM link https://websmp106.sap-ag.de/~sapidb/011000358700001225132009E (Require for S-User id)
Thanks
Sriram