Help With Stored Procedures / Dynamic Queries

Hello, I'm trying to create a Stored Procedure who receives the table name as a parameter, then uses a cursor to obtain every column name and then builds a string like SELECT col1, col2, ... from TABLE

In fact that would be the same as SELECT * FROM table; but I can't do this, because I'll be using this stored procedure to loop through many tables that has different quantity of columns with a DTS, and if a specify the *, then the DTS wouldn't let me do the select with tables with different quantity of fields.

Could you help me please, because my code isn't working:

CREATE PROCEDURE dbo.stp_Test
(
@tablename AS VARCHAR(50)
)

AS

DECLARE @columnname varchar(50)
DECLARE @strsql Nvarchar(500)
DECLARE @query varchar(4000)

SET NOCOUNT ON

DECLARE c1 CURSOR FOR
SELECT column_name FROM information_schema.columns
WHERE table_name = @tablename
OPEN c1
FETCH NEXT FROM c1 INTO @columnname
WHILE @@fetch_status = 0
BEGIN
IF (@strsql is null)
BEGIN
SET @strsql=@columnname
END
ELSE
BEGIN
SET @strsql = @strsql + ',' + @columnname
END

FETCH NEXT FROM c1 INTO @columnname
END
CLOSE c1
DEALLOCATE c1

SELECT @query = 'SELECT ' + @strsql + ' FROM ' + @tablename
EXEC @query

SET NOCOUNT OFF
GO