Getting data for edited values in update trigger in sql server

Hi ,
 
I am writing update trigger for tables in SQL server 2008 r2

i need to store values (Old value, new value ) in Log table.

How to get the old values  ?

CREATE TRIGGER trgAfterUpdate ON [dbo].[Employee_Test]
FOR UPDATE
AS
      declare @empid int;
      declare @empname varchar(100);
      declare @empsal decimal(10,2);
      declare @audit_action varchar(100);

      select @empid=i.Emp_ID from inserted i;      
      select @empname=i.Emp_Name from inserted i;      
      select @empsal=i.Emp_Sal from inserted i;      
      
      if update(Emp_Name)insert into insert into Emp_Audit
           (User_ID,System_Time,Affected_Table,Affected_Field,Old_Data,New_Data)
      values(@user_id,@InsertDate,'Emp','EMP_ID','',@empid);
      if update(Emp_Sal)
            insert into insert into Emp_Audit
           (User_ID,System_Time,Affected_Table,Affected_Field,Old_Data,New_Data)
      values(@user_id,@InsertDate,'Emp','EMP_sal','',@empsal);

      insert into insert into Emp_Audit
           (User_ID,System_Time,Affected_Table,Affected_Field,Old_Data,New_Data)
      values(@user_id,@InsertDate,'Emp','EMP_ID','',@empid);

      PRINT 'AFTER UPDATE Trigger fired.'
GO