Since you're using SQL Server 2000, you should use the SCOPE_IDENTITY() function. Create a stored procedure to do the insert and capture the assigned identity value after the insert succeeds.

CREATE TABLE myTable (
 id int IDENTITY(1,1),
 a int NULL,
 b int NULL)

CREATE PROCEDURE AddmyTable
 @newID int OUTPUT,
 @a int,
 @b int
AS
 INSERT INTO myTable (a, b) VALUES (@a, @b)
 IF @@ERROR <> 0
 BEGIN
  RETURN -1
 END
 SET @newID = SCOPE_IDENTITY()
 RETURN 0