Well a cheap and annoying way to get rid of the chirp is to use fanbelt spray on your belts and pulleys. However, that needs to be repeated every 2-3 days and is not practical.
Your belts are loose. This could be due to bad tensioners, pulleys, or even the wrong length of belt used when you last changed your belt.
Andy, I don't think we need to change the tensioner with the belt. Tensioners are very long term wear and tear items, can last over 10 years, and typically only changed when they develop problems (which may well be the case here). Please correct me if I'm wrong. I don't think I'm supposed to be changing the tensioner every 50k miles.