Installing Oracle 11g on Windows SBS 2011 64 bit
According to Oracle support document 1307195.1, Oracle's stance is:


  Microsoft Windows Small Business Server
  
  Windows Small Business Server is a product suite that bundles several
  Microsoft products, including the Windows operating system. Oracle
  Database does not certify with product suites, only operating systems
  and platforms. To distinguish whether Oracle Database certifies with a
  particular Windows Small Business Server version, find that suite's
  operating system version and consult My Oracle Support's certification
  matrix using that operating system version.


Small Business Server 2011 is based on Windows Server 2008 R2. According to the certification matrix at Oracle support, the following versions of Oracle are certified for Windows Server 2008 R2 x64:


10.2.0.5.0
11.2.0.1.0
11.2.0.2.0
11.2.0.3.0
11.2.0.4.0
12.2.0.1.0