2 different lasers.
Just to be absolutely sure, you made the Samsung drive, the first boot device in the BIOS?
If that's definitely the case, and it still wouldn't boot your XP disc, then it does sound like the CD part is damaged, or has died completely (was this drive new when you got it?).
However, trying it on another PC is always worth a go, if you have access to another one with a spare SATA connection.