The first difference that you will note is that the prices greatly vary. This tells you that the specifications also have to be different. Therefore to begin to get a better understanding of the particular specs that you may want in your ThinkPad, a closer look at the components used is in order.

Although all T42 ThinkPad's are equipped with the same CPU Processor, namely the Pentium M type, the clock speed ranges widely between 1.5GHz and 2.1 GHz. Your choice of what processor speed to go for will be guided by two main factors. What you want to use your ThinkPad for and your available budget. For instance heavy graphics and video editing will naturally require higher processor speeds.

Still on the subject of speed, the RAM also differs ranging between 256MB to 1GB DDR SDRAM. It is useful for you to note that the T42 ThinkPad's that IBM ships, all have a 333MHz high speed RAM.

The combination of the RAM and processor speed to match the most common tasks and applications that you will be using with your ThinkPad will determine how fast you will be getting things done.

You will also need to decide on the hard drive capacity you want, which goes with an RPM speed. For the T42 ThinkPad, this ranges from 5400 on the basic low-end models to 7200 on the top range.

For most folks, the display size will not make much of a difference and will hardly be considered. For the few in graphic and video applications amongst others, the display size may be critical for what they want to achieve with their ThinkPad. There are basically two display size options for the ThinkPad. 14.1" and 15". The first will give you a limit of 1024x768 pixels maximum resolution while the other is capable of 1400x1050.

In addition, there are a number of Graphic Processors to choose from for your ThinkPad. They include:

- The ATI MOBILITY FireGL T2
- The ATI MOBILITY RADEON 7500
- The ATI MOBILITY RADEON 9000
- The ATI MOBILITY RADEON 9600

You will also need to decide on what CD/DVD combination you want for your T42 ThinkPad. You can go for the basic DVD-ROM only. Or you can settle for the top of the range re-writable DVD and CD combo. A choice of DVD burner is also available.

Expandability options are available as follows;

1 x Type I/II PC Card Slot
1 x Type III PC Card Slot
2 x Type I/II PC Card Slot
2 x Type III PC Card Slot
Digital Camera (CCD/CMOS)
Docking Station/Port Replicator

You can also go for a ThinkPad with Finger Print Sensor technology, for a premium price tag, of course.

Ultimately the decisions you make on the specs that you would like for your T42 ThinkPad model will greatly influence the final weight which could range from 4.9lbs to 6.2lbs. This is important to keep a close eye on because there are people to whom the weight will be important.