Monitoring SQL Server 10.50.1600 (2008 R2)
I couldn't find "Microsoft SQL Server" in the drop down as i could find it in other windows server with 2005 database running in there. As per the documentation:
Versions Supported
This plug-in supports the following versions of products:
Enterprise Manager 11g Grid Control Release 1 (11.1.0.1) or higher (Oracle Management Service and Oracle Management Agent)
OR
Enterprise Manager 10g Grid Control Release 3 (10.2.0.3) or higher, with Oracle Management Agent 10g Release 2 (10.2.0.1) or higher for Microsoft Windows