IBM ThinkPad T42 cheap

The speed at which the CPU processes information internally is measured in MegaHertz (MHz) and GigaHertz (GHz). 1 GHz is equal to 1,000 MHz.

It's difficult to upgrade a laptop's hard drive, so make sure the one you originally get is big enough for your needs. If you're buying a desktop-replacement system, go for at least 100GB. If you'll be using it on the road you may not need as much.

An optical drive allows your computer to read data from a disc. Types of optical drive include CDR, CDRW, DVD, DVD-RW, DVD RAM & Blu-ray.

An operating system is a program designed to run other programs on a computer. Windows OS include XP, Vista and Windows 7 with MAC computers supporting Leopard and Snow Leopard.

Common display types include WXGA, XGA and TFT. The latest netbooks and some laptops now support LED back lit screens which provide higher image clarity.

The screen resolution signifies the number of pixels on the entire screen. For example, a 800-by-600 pixel screen is capable of displaying 800 distinct pixels on each of 600 lines. The higher the screen resolution the clearer the image.

The higher the memory the better your games and applications will look and run. If you want to play the latest games on your laptop then you should aim for either 512MB or 1GB memory.

With the use of a webcam, you can communicate with friends and family through a host of applications such as Skype and MSN Messenger. The most common webcam resolution is 1.3MP however external webcams can be much higher.

Wired networking will allow you to connect your computer to the internet via the use of a network cable and an ethernet port.

Wireless networking allows you to connect your computer to a wireless access point. The beauty of this is that no cables are required, allowing you to browse the web anywhere around the home or office.