I've been trying out two new notebooks, each designed to pack powerful performance into a package that's thinner and lighter than many mainstream notebooks. They're not direct competitors with one another; one is a PC running Windows Vista and the other is a Mac. But each represents their makers' latest and best attempts at offering a desktop replacement that's ideal for traveling with extended battery life.

Lenovo ThinkPad T400s

The T400s morphs the thinness of Lenovo's breakthrough "thin and light" X300 with its older T400, incorporating a 14.1-inch display, a solid-state drive and a new mechanical design to keep it just 0.83 inches thick. A new carbon fiber mechanical structure provides exceptional rigidity and yet adds little weight. The T400s weighs just under four pounds, 20 percent lighter than the T400.

My sample was equipped with Windows Vista Business, an Intel Core Duo (2.53GHz) processor, a 1440 x 900 WXGA display, 2GB memory, a 128GB SSD, Optical Drive: DVDRW, WiFi, Intel integrated Graphics X4500M, 6-cell battery (44Wh) and a 2GB camera. It measures 13.3 x 9.5 x 0.83 inches and costs $2,130. (Other T400s configurations start at $1,600).

The appearance is similar to other ThinkPads with its matte black finish. The six-cell battery is built into the main housing without extending beyond the hinge. A larger battery and a dock are available as accessories.

One of the ThinkPad's greatest strengths has been its keyboards, and this model exhibits further refinement. The delete and escape keys have been enlarged and are vertically shaped, making them easier to find. The gaps between the keys have been tightened to help prevent crumbs and hairs from getting into the keyswitches.

The touchpad is now flush with the palm rest and has a new heavily textured surface that allows users to feel its location without looking down. I found the roughness to make it feel a little less precise. The touchpad allows two-finger zooming to change a window size and rotate images, much like the iPhone and MacBooks. There's also a track stick, a mainstay of ThinkPads.

The LED-backlit display is brighter than on previous ThinkPads I've used. Some of the buttons and switches are newly designed and repositioned, including an illuminated power button and buttons to control video and audio. There's a full array of connectors and ports, including three USB ports and the standard video connector that connects to a projector. But, surprisingly, an SD card slot is extra.

Battery life with the screen just below full brightness was slightly more than four hours, very good performance, but far less than the rated eight hours. All notebook manufacturers need to get real with their rating numbers. My advice is to halve whatever they say.

Performance was typical of notebooks with the 2.53GHz Intel Core Duo processor running Vista. But no matter how much effort the notebook designers put into improving performance, Vista limits the speed with its security checks and overall sluggishness. For example, resume time from sleep was 45 seconds, compared to the Mac's six seconds. That's not much of an improvement over PCs from many years ago. Nevertheless, based on its size, features, battery life and performance, the T400s should be a big success, especially for business people on the road.

MacBook Pro 15-inch

Apple takes a different design approach to notebooks than Lenovo, or any other notebook maker, for that matter. The company is obsessed (in a good way) with appearance and finish, albeit at the sacrifice of some features standard on PCs.

Stiffness and structure is created by its enclosure, with each piece machined out of a solid block of aluminum. The result is a very sturdy housing, beautifully finished, with no gaps and few trim parts. Even the square holes for the keys are individually machined, eliminating gaps around them. Its keyboard has an excellent feel, although not quite up to the ThinkPad. The keys are backlit for typing in a dark room, while the ThinkPad has an LED that illuminates the keyboard from the top, a less effective solution

The 15-inch MacBook Pro's entry model comes with 4GB memory and a 250GB hard drive. It only has two USB ports, adjacent to one another, making it awkward to use one port when using a memory stick or modem in the other. It has no standard video output and needs an adapter to connect a projector. There is now an SD card slot, the first appearing on a MacBook.

The trackpad is now much larger and is used as the left button by pushing anywhere on its surface. The bottom corner can be set to be the right button. The pad can be used for zooming and rotating.

The MacBook Pro costs $1,700 with other models costing up to $2,000. That makes it a few hundred dollars less expensive than the T400s, although there are some differences, the major being the Pro is heavier and larger. The Pro comes with the same processor, 4GB versus 2GB, and 250GB hard drive vs. a more expensive 128GB SSD. It has a slightly larger 15-inch (1440 by 900) display compared with the 14-inch display on the ThinkPad. But the screen has a wider color gamut and a more neutral white, producing some shades of colors I've not seen before on a notebook.

The other major difference is a new battery in the Mac that's sealed inside, replaceable only by Apple. It's rated at seven hours, but provided about 3.5 hours in normal use with near-full screen brightness. The Pro measures 14.4 x 9.8 x 1.0 inches and weighs 5.4 pounds, noticeably heavier than the ThinkPad and one of the biggest disadvantages of the Pro.

While Windows users will prefer the ThinkPad and Mac users the MacBook Pro, each offers excellent performance, with the Mac surprisingly being several hundred dollars less expensive. Thin and light does cost.

While the aluminum MacBooks are well worth showing off, one of the most popular accessories is InCase's (goincase.com) two-piece precision-molded hard plastic shell that snaps onto the lid and bottom housing. It has a rubberized finish and is available in several colors ($50). The company also makes a 15-inch colored neoprene case in assorted colors that work with both the MacBook Pro and the IBM T400s. ($35)