IMO the buds that come with iPods are crap.
Koss ones are great and at less the $20 I don't get upset if I get them caught on something and break a pair.
Read what other users say about them
http://www.amazon.com/gp/product/B00...Fencoding=UTF8
Actually I always bought these Koss buds but last time the above ones was what was in stock. They both seem to sound the same.
http://www.amazon.com/gp/product/B00...Fencoding=UTF8
No idea really about if you might have warranty issues with that Powerbook but at that price I would risk it.