Well, your P15 has only 3 USB 2.0 ports, and no serial ports, so you will need an adapter of some sorts.
This may work for you:
USB to Serial adapter at Best BuyOr this:
Belkin USB to Serial adapter This may work too:
Port ReplicatorAlso, there is no "Line Out" for the sound card built-in to that laptop, so you'll probably want to get either a USB sound module, or some kind of PCMCIA sound card, for the best results.
Good luck!