Hi Arijit.
New SAP projects and installation should be on Oracle 11g.
Firstly, you do not have to pay additional payment to Oracle (because free extended support is over now and 10.2 is no longer supported. also you are not allwoed to download patches from marketplace if you do not have an extended support contract with Oracle itself), secondly with 11g you do not have to modify any file to accept Windows 2008.
Regards,
János