How important is mobility?
The degree of mobility of your notebook is a combination of size, weight and battery life. You will need to consider how often you will be carrying it around and if you will mainly be relying on the notebook's battery or an external power source. Notebooks generally weigh around 3-4kg, but they can weigh as little as 1.5kg and as much as 6kg, depending on the model and features included.
A lighter notebook may not have an internal CD/DVD drive, may have a smaller screen, or reduced storage capabilities. Alternatively, the larger (and much heavier) desktop-replacement machines usually have worse battery life because of their big power-draining screens and components. However, they can feature all the trimmings such as CD/DVD drives and even high-definition Blu-ray or HD-DVD drives, multiple hard disks, cutting-edge mobile graphics, widescreen displays up to 20in and full-sized keyboards, complete with dedicated number pads.
Notebooks weigh around 3kg, with some hovering around the 2kg or less mark. These particular weights are for the notebook itself, not including the power supply or often-used accessories such as external drives. It's worth keeping this in mind when making your purchase. Power supplied and other accessories can add considerable weight to the bag.
Notebooks now mostly use Lithium Ion (Li-Ion) batteries that operate for one to three hours on a single battery charge. However, if you use all of the power saving options available, and depending on the number of cells in the battery (the more cells, the longer it lasts), a Li-Ion battery can last up to six or seven hours.
What will I be using the notebook for?
If you won't be travelling frequently with your notebook, then battery life and weight will not be a primary concern. Instead, you may want to concentrate on ramping up the processor, screen size and memory. If, however, you will be carting your notebook around with you on a regular basis -- travelling interstate or overseas, around a university, or perhaps you frequently work away from the office -- the size and weight of your notebook, and its battery life, become more important.
You may prefer to scrimp on the size of the display to lighten the load, so opt for a 12, 13.3 or 14in instead of 15-15.4in or 17in widescreen varieties. If you don't play games, edit video or watch DVD movies, there's little point buying a model with the latest mobile graphics card because a built-in chip (integrated graphics) should meet your needs. If, however, the graphics capabilities and size of the screen are important, this may not be the best option.
Also, there's nothing to say that you have to buy a model with everything you want already included. Consider buying a basic unit and adding to it. It could work out a lot cheaper to obtain things such an external TV card and DVD writer when the need arises.
If you only want a notebook to store such things as contacts, and occasionally enter small amounts of data, a PDA (personal digital assistant) or some of the current mobile phones may be more suitable to your needs. These devices are reliable, run for days or even weeks on a single charge, and can be carried more or less anywhere.