These can be connected externally as well, as can a mouse. In place of a mouse, portable computers have a touch pad or a roller, both of which can be awkward for the new user at first. On the sound side, remember, a laptop's sound quality is not the same as that of a desktop. Size and weight are probably the most important factors to be considered while choosing a laptop. Apart from the computer itself, you will have to carry power cables, external drives, if any, and floppies and CDs, not to mention the carry bag itself.
Size is also important.
One can be tempted by a tiny system, but that means a smaller display area. It also means a cramped keyboard, which can be a pain at the best of times. The other important consideration related to portability is how much battery back-up it has and how long it takes to recharge. It need not be spelt out, but the longer it can run on batteries and the faster it can recharge, the better. Those who have been around laptops may have noticed that in some machines one cannot see anything on the screen unless one is right in front of it.