Most likely a loose (not bad) belt. Do either one of them deflect alot if you push on them? Both the alternator and power steering belts get tensioned the same way (in my car anyway). When the engine is off, there's a bolt you loosen that allows the p/s or alternator to hinge. With one hand, you pull the device with your hand to tension it, then with the other hand you tighten the bolt. Anyone else, feel free to elaborate on that or give some info on other ways that he might need to tension his belts.