declare @StartDate date , 
        @EndDate date 
select @StartDate = '20100101',
       @EndDate = '20100131'
-- the above lines are to demonstrate this code without being a stored procedure
-- remark out the following line to create the procedure, and then call it
-- with your starting /ending dates.
-- CREATE PROCEDURE dbo.AddDates (@StartDate date, @EndDate date) AS
;WITH
 TENS      (N) AS (SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL 
                   SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL 
                   SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0),
THOUSANDS (N) AS (SELECT 1 FROM TENS t1 CROSS JOIN TENS t2 CROSS JOIN TENS t3),
MILLIONS  (N) AS (SELECT 1 FROM THOUSANDS t1 CROSS JOIN THOUSANDS t2),
TALLY     (N) AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM MILLIONS)
select @StartDate UNION ALL
select dateadd(day, N, @StartDate)
  from Tally
 where N <= datediff(day, @STartDAte, @EndDate)