There are two types -- macbook and macbook pro. Both will do internet speedily and very well. Both are equally very reliable. However, the macbook pro is faster -- although you won't notice a speed difference with the Internet, just on apps that use more CPU for crunching data and algorithms (like Photoshop, iMovie, etc.).
If you're a successful trader (i.e., you make lots of money), get a macbook pro. You will want the larger screen. (The macbook pro comes in 15" and 17" screens; the macbook has only 13".)