SBS 2011 is based on Server 2008 R2, so those are the drivers you should be using.  Make sure you are using this file (extracted first): www.dell.com/.../DriverDetails Also, you must configure RAID BEFORE booting to the Windows DVD.
I have successfully configured the RAID 1 configuration through the S100 configuration. I am trying to install SBS 2011 Standard x64 and am having trouble with regards to the install recognising drivers for the RAID config. Given I cannot locate SBS 2011 drivers for the R210 I have been trying every set of drivers for the S100 I could find. None have been recognised as compatible by the SBS install process and none of the listed incompatible drivers have worked. I always get 'No new devices could be found....' Can someone help me with this as i'm not far away from seeing how well the R210 II floats in the swimming pool! The service tag is [ADMIN NOTE: Service Tag removed per privacy policy]
SBS 2011 RAID 1 issues with PERC S100 in R210 II