Living up to the sub-notebook name, this portable system from IBM represents one of the best instances of miniaturised engineering. The IBM ThinkPad 240 was the lightest portable in this month's Lab, which makes it ideal for the ultimate road warrior looking for a feather-weight system. In many ways, the ThinkPad 240 shares many similarities with Acer's TravelMate 310, the predecessor to the TravelMate 340T. The 240 sports a similar form factor as well as a built-in modem - important features of the original TravelMate 310.

The IBM ThinkPad 240 has a very definite and specific purpose and, as a result, it may not be the ideal solution for every user. This machine is clearly targeted at users who want a lean machine with no extras. The 240 comes with an external floppy drive which connects to the machine via a proprietary expansion port but it doesn't come with a CD-ROM drive.

This caused us no end of trouble when we wanted to load on software and it's something worth considering if you wish to purchase the ThinkPad 240. An external CD-ROM drive is available for an extra charge that may be worthwhile considering the only alternative to loading software on to the system is via a floppy or via PC-Card-based network adapter over a network.

Despite the fact that the 240 is an ultralight notebook, IBM has done an excellent job of making the system's RAM and hard drive easy to upgrade. The 10mm thick hard drive is fixed within a plastic module that can be taken out easily by removing two screws. The one free RAM slot is situated under the keyboard which needs three screws to be removed from the base in order for it to be possible to lift out. Unlike many systems where the keyboard is lifted out, the 240's keyboard is very solid and does not buckle under pressure. In fact, the keyboard is one of the excellent features of this notebook since the keys are almost full-sized and easy to type at for long periods of time.

This compact and well put-together system does come at a price and that is performance. The IBM ThinkPad 240, with its Celeron/366 CPU was one of the slower systems in this month's Labs in almost all our tests. However, it must be remembered that this machine is not a desktop replacement and is instead designed to be a highly portable system.