you can use a cursor to achieve this...but nvarchar datatype has a limitation of 4000 char..
Code:
DECLARE @Name as nvarchar(64)
DECLARE @RowToCol as nvarchar(4000)
SET @RowToCol = ''
DECLARE Employee_Cursor CURSOR FOR
SELECT Emp_Name FROM Employee
OPEN Employee_Cursor
FETCH NEXT FROM Employee_Cursor
WHILE @@FETCH_STATUS = 0
BEGIN
   FETCH NEXT FROM Employee_Cursor INTO @Name
   SET 	@RowToCol = @RowToCol + ' ' + @Name
END
CLOSE Employee_Cursor
DEALLOCATE Employee_Cursor

SELECT @RowToCol