Use this.
EXECUTE AS USER = 'Wanida'; -- User name
SELECT * FROM fn_my_permissions('HumanResources.Employee', 'OBJECT')
ORDER BY subentity_name, permission_name ;
REVERT;
GO
more details.
http://www.mssqltips.com/sqlservertip/1440/script-to-determine-permissions-in-sql-server-2005/