Typically, trading with a powerful desktop PC is more advantageous (and cheaper) than with a laptop. Since a PC has more space for components, it can be configured for more speed and processing power than a portable computer. A laptop has limited space, so it requires smaller and more expensive components. Consequently, a very high end laptop will be a lot more expensive than a PC with similar performance.
The other issue with laptops is that it is more cumbersome to connect multiple monitors to it. Even though you can connect an extra monitor to most laptops (via a VGA or DVI port), it is kind of awkward and unsymmetrical to be trading while looking at the laptop screen and at a bigger screen right next to it!
Nevertheless, if a trader wants mobility, a laptop might have to do. In fact, there are many traders that don’t need to get a standalone PC at all. For example, traders who run automated systems (also known as robots or algorithms [algos]). These traders normally install their systems on a VPS (virtual private server). This is a remote server that is either collocated or geographically close to the broker’s execution server to minimize latency (or delay in the transmission and receipt of trade orders); so the actual trades are coming from this remote server and not from the trader’s actual computer. As a result, these kind of algorithmic traders can easily get by with a laptop.
If you already have a pretty high end laptop and you don’t want to spend extra money on a desktop computer, then at least get a separate monitor and connect it to the appropriate port on the back of the laptop (something is better than nothing).
If you prefer a laptop, an even better option is to order USB video adapters to connect two or more extra monitors. I have personally used adapters from Plugable (like this one)). You’ll need one USB adapter for each monitor you would like to connect to your laptop (for example, 4 extra monitors = 4 USB adapters). Since your laptop will normally not have many available USB ports, it’s usually a good idea to also get a powered USB hub (like this one) if you want to trade with two or more extra screens.
Finally, make sure to get a laptop with as much RAM as possible (8 GB or more if possible).
Go to the computer section if you need professional help with any of this.