mysql question about duplicates

the-story

So, I have a table (simpleified greatly)

CREATE TABLE `participants` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `program_id` int(11) NOT NULL,
  `user_key` varchar(64) NOT NULL,
  PRIMARY KEY (`id`),
);

I run this:

select count(*) as tot, program_id, user_key from participants group by program_id, user_key having count(*) > 1 order by count(*);

and get 1485 rows in response some with tot as high as 128...

How can I get the id's of the 3579 rows that make up those grouped results?

(prgram_id, user_key should have originally been a unique key; now I need to enforce it so I need to decide which of the duplicates to delete.  Having their individual id will allow me to see which one haven't joined ot any other thbles and can therefore just be deleted.) 

select p2.id from participants p2 join (select program_id, user_key from participants group by program_id, user_key having count(id) > 1 order by count(id)) p1 on p1.program_id = p2.program_id and p1.user_key = p2.user_key;

Does the trick.