MacBook 2007 charger
The adapter that you should get is the 60W Magsafe with "T" Connector.  From Apple's Support site:



That said, I would get an Apple 85W adapter instead of the 60W.  You will have more versatility if you decide to upgrade your MacBook to a different model down the road.  You won't do any damage, 85W just means that's the maximum power draw the adapter will support, not that it will push that amount to your computer.