My MacBook didn't come with a mouse - it simply has a built in trackpad with a single button. I remember one of my early criticisms of the Mac was that it only has a one button mouse - but you got so much power out of right clicking capabilities! Well, Mac does indeed support right clicking - and it's great for accessing sub menus much like I'm used to in Windows.
Unfortunately the trackpad doesn't have two buttons - only a single large button. But how would I be able to scroll through a web page easily? Or right click when I only had 1 mouse button??? Fortunately the trackpad supports a couple of gestures that make it really easy (and surprisingly natural) to do both. I can scroll a web page by simply placing two fingers on the trackpad and moving them up or down. If I want to right-click an item I move the mouse pointer to the item I want to right-click, place a second finger on the trackpad and then click. It only took a few minutes to get used to it - makes me wish my HP laptop did this.
Even with the trackpad working pretty well I decided to get a new mouse. I've always been a huge Logitech fan and they had a wired laser mouse that looked pretty impressive: The MX400. Great mouse and it listed itself as Mac compatible. I simply took it out of the box, plugged it in and it worked like a charm.
The only thing it did not do was make the little Forward and Backward buttons work in Safari or Firefox. Turns out I needed to go up to the Logitech web site and download and install the Logitech Control Center. Simple install and now I could completely customize the buttons on the mouse.
While I'm very comfortable using the trackpad on my MacBook, the external mouse from Logitech is a very welcome addition.