I have a second hand MacBook but I don’t use it much, main reason is that I hate the track pad and when I use a mouse with it it ‘feels’ wrong. Hard to describe just what it is but it’s like the cursor is just not moving the right way. I did find a little tool that has helped but I’m still a little put off by the whole feel of the mouse. Maybe this will help you if you are also suffering from ‘odd mouse’ syndrome.
Mouse Acceleration Preference Pane for Mac OS X.