4. Optical

If you want an optical drive, you're going to have to carry it; the drive and electronics to control it add size and weight. Only a few of what we'd consider true ultraportables have a built-in optical drive: the Lenovo V100, Sharp M4000 WideNote and Sony VAIO SZ all weigh in at around 3.8 lbs with an optical drive while the HP TC2400 manages to fit it in at just 2.8 lbs.

Some models bundle an external drive in the price; if not they're widely available, or you can share an optical drive over a network just like a hard drive. Either way what you get is usually a combo CD-RW and DVD-ROM drive rather than a DVD burner although again the HP TC2400 is an honorable exception with a DVD+/-RW drive.

Portable Power

A smaller notebook means a smaller battery but it doesn't have to mean a shorter battery life, especially if you add on an extra battery. The smaller screen and no optical drive mean you're using less power already. The secondary battery for a Toshiba Portege R200 clips underneath the keyboard. It only adds 10 oz to the 2.7-lb weight and takes the 0.7" body up to a full inch for a 3" strip at the back, giving you a better angle for typing. But if you turn off Wi-Fi and choose the long-life low power settings you can work for up to eight hours. Lenovo has a similar battery for the X41 though it adds more weight and less power. Sony managed almost 10 hours of real world use with the VAIO TX as well. Not every ultraportable manages that well, and with only a single battery, you may only see two or three hours of use.

The ultraslim Toshiba Portege R200 offers excellent battery life with an equally lightweight extra battery.

The tiny Fujitsu-Siemens Lifebook P1510 has an extra battery that clips on to the front of the keyboard (it works well as a wrist rest) and takes the battery life from two hours 20 minutes up to a little over five hours.

You can't complain about performance if you get a notebook with a Core 2 Duo, although some models stick with single core to keep the power down. But check the hard drive and memory in the system, too, as these are what will slow things down if you e want to perform demanding tasks like image or video editing. While 60 GB and 80 GB drives are common, they are not as large as you might want. And many systems start with 512 MB of RAM; check the price for the 1 GB you really want. Look for access panels on the base that will let you swap out the hard drive or upgrade the memory; otherwise you'll have to send an ultraportable back to have it opened and upgraded professionally if you're not very confident about disassembling the device.

The smaller the notebook the less powerful the integrated graphics system is likely to be; don't expect to be playing 3D games on anything except the most expensive (or largest) ultraportable. If that matters to you, check out the Sony VAIO SZ, which has a physical switch to swap between integrated graphics for low power and the NVIDIA GeForce card for speed. The quality of screens is usually good; ultraportables are premium PCs. Slate Tablet PCs often come with the option of a brighter screen with a filter coating to make it visible in bright sunlight, usually combined with an ambient light sensor so you're not wasting power indoors. That's not always true of the smaller sub-notebooks, especially if they have a passive touch screen which makes for a dimmer picture.

Very small sub-notebooks like the Fujitsu Siemens Lifebook sacrifice power, ports and graphics in the name of portability.

Expect a limited number of ports; probably two USB 2, VGA, 100 MBps Ethernet (or occasionally Gigabit Ethernet as on the HP TC2400), modem, PC Card - or increasingly Express Card - and not much else. SD card slots are quite common; larger portables may have a multiple memory card reader and a FireWire port. Some have a port for a docking station or port replicator. We haven't seen eSATA ports on an ultraportable yet.