Are any kind of wood-chips good enough for smoking?

I was watching a Heston Blumenthal Show called "Cooking like Heston" the other day, the episode was on potatoes and he made doughnuts using them. one of the things he did to prepare the potatos for the doughnut mixture was to smoke them using wood-chips.

I have seen wood-chips be used by him, Jamie Oliver and on Iron Chef (Japan) and Master Chef (Australia) a few times and i've been wondering if any kind of wood-chips can be used to do smoking (ie. ones picked up from the gardening section of a hardware store or made by myself from junk off cuts from trees or building material) or if i should be looking out for a particular kind which is meant for cooking.