Considering the age of your computer if you are going to open it anyway I would change the battery. The battery you have found looks right and I have never had any problems with a generic CR2032. As a further guide I am including a link to a "proper" CR2032 so you can compare. Good luck with your upgrade--just remember to go slow and enjoy the process.
http://eshop.macsales.com/item/NewerTech/CR2032/