ummm… i have no clue what they did, but when i took my macbook pro to the mac store (after dropping it) i told them it broke and played dumb and got a new hd 
Good thing i do a weekly backup, and it was monday so i lost nothing 
And when i got it back, it ran way faster…
Anyways, i dont know much about power pc macs so i cant help you much, and i think theyre a bit different… Try reseating the nvram or somethign like that, it might help… um… Yea… If you can do a compleate backup with superduper! and then format the drive with the os x dvd 1 with disk utility, then zero it out, and boot off the backup by holding down option on startup, then rebackup everytjing using super duper back onto the internal drive, it should speed it up a decent bit on a older comp