The original posting was on my mind last night as I was cooking some chicken to put into a big batch of Brunswick stew. I intentionally pulled a leg out when it wasn't quite cooked enough, and it was truly "rubbery."
I don't claim to be a great cook, but here are some other things that I thought that I'd throw into this conversation.
One tool that I really like to use for cooking chicken is a cast iron Dutch Oven. You can find them, reasonably priced, even at places like
WalMart. If you put your chicken into one of these things, then put a cup or so of water at the bottom (you can add flavorings or veggies to the liquid ... like boullion ... if spell check will let me find a way to spell it that it approves of). Put the top all the way on it and put the thing into your oven. Cook the chicken for half the time required for its weight (see otherr postings) and then reach in and take the top off and cook it for the rest of the time. That gives me moist meat, properly cooked, without it drying. Taking the top off for half the time also helps to brown the skin. I'm a huge fan of cast iron, BTW. Once you learn how use it and to care for it, and you take care of it properly, it's fast to clean up and can be virtually stick-free. Grandma knew what she was doing, and she didn't have any teflon potentially releasing chemicals for your family to breathe in.
Piercing the chicken to see if the juices are clear is absolutely a good way to tell when it's cooked, but it also releases some of the juices. Another "trick" is to grab the end of a drumstick (with a cloth ... it's hot) and gently try to twist the bone. If the bone twists free easily, the chicken is going to be cooked properly and it doesn't release any of the juices in the breast meat.
Also, make sure that when you take your chicken out of the oven you let it rest for 10-15 minutes. If you cut into meat when it's fresh out of the oven, the juices are going to flow out of it and add to it being dry.