One of the first things I do when I purchase a new computer is add as much additional RAM as I can. With a Macbook, the RAM comes in pairs, which means that you use a pair of identical RAM sticks at the same time.
The new aluminum Macbooks are a little more tricky to add RAM over the previous models. Previously, the RAM slots were accessed through the battery compartment. However, the new Macbooks take a little bit more work to access and replace the RAM.
The complete step-by-step tutorial with plenty of helpful picures are found at Wired.com in their new article How-To: Adding RAM to Unibody MacBooks.
If you’re looking to purchase a new Macbook anytime soon or if you already own one and are thinking about adding more RAM, it is a really great article which I suggest you check out.