WHAT'S HOT: The Sharp PC-UM20 is one of the thinnest notebooks you can buy. The silver unit with a dark keyboard measures just three-quarters of an inch tall with the lid closed and weighs 2.9 pounds without peripherals. It has a 12.1-inch screen--far from the largest available, but impressive for a notebook this thin and lightweight.

WHAT'S NOT: Battery life hasn't gotten any better with this latest installment in Sharp's UM series. The PC-UM20 lasted just 2.2 hours on one charge, the same as the PC-UM10 we tested a few months ago. Sharp claims that the $349, 0.8-pound 12-cell replacement battery will last up to 9 hours (we didn't test it, though). The ultrathin PC-UM20 lacks built-in parallel, serial, and PS/2 connections and requires a short, proprietary VGA adapter cable (included with the notebook) for attaching an external monitor. An optional $129 port bar adds all the missing connections, including a standard VGA monitor connection, and throws in two additional USB 1.1 ports for a total of three. However, you can't get a docking station, so internal drive bays and stereo speakers aren't available for this notebook; you're stuck with the PC-UM20's monaural sound. An external USB 1.1 6X CD-ROM drive will cost an extra $100, a USB 1.1 floppy drive $99. The memory and built-in storage can't be upgraded; the sealed case design blocks access to both parts.

WHAT ELSE: The PC-UM20 includes just a handful of built-in connections: headphones and microphone ports, one USB 1.1 port, modem and ethernet jacks, and one PC Card slot. The narrow edge of the battery forms the back of the unit. Removing the battery requires squeezing two release levers inward simultaneously. Built-in wireless connectivity is not an option with the PC-UM20.

Its subsize keyboard is simply designed, with no hot-launch buttons or Windows shortcut keys. According to Sharp, the keys are retractable; they pop up to a full 3mm travel distance when you open the lid. We found typing passable--paging up and down requires inconvenient combination keystrokes--but the keyboard didn't feel especially roomy, and the key travel didn't seem particularly deep to us. Including all its accessories--the USB CD-ROM drive, USB floppy drive, port bar, and VGA adapter--the PC-UM20 weighs 5.5 pounds.

Considering it uses the ultralow-voltage Pentium III-750/350 processor, the PC-UM20 performed well in our application-based benchmark tests. Using Windows XP Professional (the older Windows 2000 Professional also comes installed as an option; you can choose which OS you want to use when you start the system up for the first time), it earned a PC WorldBench 4 score of 89. Sharp bundles a helpful printed operation manual, but no on-screen, electronic manual.

UPSHOT: At $1799 with the external CD-ROM drive, the Sharp PC-UM20 is priced well for an ultraportable. It's a relatively simple little machine that lacks legacy ports and isn't upgradeable. It's incredibly thin and light, however, and it nipped at the heels of many full-size laptops in our speed tests. If 2.2-hour battery life is enough for you, the budget-priced PC-UM20 makes a good lean, mean travel machine.

SUMMARY

Sharp PC-UM20 PC WorldBench 4 score of 89, Pentium III-M-ULV750/350 CPU, 256MB of PC100 SDRAM, 512KB L2 cache, Windows XP Professional, 12.1-inch active-matrix screen, ATI Rage Mobility M graphics chip with 4MB of SDRAM, 20GB hard drive, 6X DVD-ROM drive, built-in V.90 modem and network adapter, touchpad pointing device, 3.6 pounds (including AC adapter and VGA cable). One-year parts and labor warranty, free unlimited 24-hour toll-free tech support. $1799 800/237-4277 www.sharp-business.com