The following guide will help you think about the top few items when buying a laptop computer. It's not exhuastive by any means, but is a good general rule of thumb to follow.

Processing power: Think about the amount of processing power you will need in the future. Although you may not use all the processing power now, the extra investment now may result in your computer being outdated much slower than it would otherwise.

Memory: Much like processing power, get more than you need. Memory is relatively cheap, and it may give you that extra few months/years of use on your computer.

Disk space: This is cheap! Always get more than you need as you will run out much more quickly than you ever thought.

Size (laptops): How you use the computer will dictate the size you should get. If you find yourself carrying the computer around a lot, you most likely want something that is more portable (i.e. smaller). There are many computers these days that have separate media stations. This means you don't have to always carry around the extra weight of external drives and ports. Just plug them into your computer when you need them. That said, you may only occasionally carry your laptop around. If this is the case, you may want something larger so you have more power and a larger screen size.

Durability: You want to make sure the computer is durable, especially if it is a laptop. From personal experience, IBM ThinkPads are one of the most durable and well-designed laptos I've ever used.

Software: It is generally good to get a good basic set of software pre-loaded on your computer, especially if you don't own your own copies. It's often much cheaper than purchasing it yourself after you get the computer. That said, don't purchase and pre-load your computer with every piece of software the manufacturer is selling.

Extended warranty: In general, these are not worth purchasing, especially if you take care of your electronics.

I hope this helps! Good luck with your purchase!