What you do get with low-voltage processors is all-day battery life. The T60 Tablet managed to rack up 5 hours and 17 minutes on MobileMark 2007, thanks to its low-voltage processor and 66-Wh battery. By contrast, the Fujitsu and HP tablets have the potential for longer battery life because of their lower-powered processors. The HP 2710p achieved 4 hours 45 minutes on MobileMark 2007—an astonishing feat with its smaller, 44-Wh battery.

IBM's overall tablet design hasn't changed since the ThinkPad T40 Tablet first launched in 2005. The magnesium alloy–backed frame and the pitch-black ID are no different from those of the rest of the ThinkPad line. The frame guards against wear and tear, and the conservative black trim lets people know that this machine means business. The T40 Tablet was one of the lightest tablets around, but lately, the competition has been growing fierce. The T60's 66-Wh extended battery boosts the weight to 4.4 pounds. Meanwhile, the Fujitsu Lifebook T2010 is able to keep things under 4 pounds with its 93-Wh extended battery. Opting for a 4-cell battery and saving $50 can get the T60 Tablet under 4 pounds, but it would leave you with appallingly short battery life. On the other hand, the HP Compaq 2710p can get away with its 44-Wh battery, since it's using extremely low-powered components.

The trend in laptops is toward widescreens, even on tablets. IBM, however, is holding firm with the T60's standard screen. The Fujitsu T2010, the HP Compaq 2710p, and the Gateway C-120X have 12-inch widescreens optimized for multimedia tasks, while the standard-screen T60 is geared toward office work. The matte screen on the T60 Tablet offsets a lot of the glare coming from external lighting directed at the screen. In contrast, the intensely bright glossy screen on the Fujitsu T2010 is great for color-rich projects, but does little to minimize glare.

Hands down, the ThinkPad T60 Tablet provides the best typing experience in the business. Its full-size keyboard is unmatched, and the TrackPoint pointing stick technology is one of a kind. The HP 2710p comes close, but its pointing stick is too stiff for my taste. The Fujitsu T2010 has a responsive pointing stick, but its keyboard doesn't give the satisfying resistance provided by the T60 Tablet's keyboard. Rotating the screen to write on these convertible tablets makes them more equal. A good portion of the writing experience is dependent on the operating system; all of the above mentioned tablets load Windows Vista Business, which has an optimized tablet interface built in. On all of them, the writing recognition is terrific and can be further improved by Vista's Tablet PC Pen Training application. The pen-on-screen feel and the feel of the digitizer pen in your hand are what distinguish the tablets from one another. Writing on the T60, as on most tablets, involves light strokes. You don't have to press as hard as when writing on a piece of paper, so your hands don't tire as fast. The digitizer pen has a rubber grip in the middle that increases the comfort level, though I wish the pen had a little more girth, like the one found on the Motion Computing LE1700.

As for features, the only thing missing on the ThinkPad T60 Tablet is a built-in optical drive. But every convertible tablet is a compromise: You either want the lightest system possible, or opt for a heavier system with the ability to watch DVDs and install software. For example, the Gateway C-120X approaches 5 pounds with its built-in dual-layer DVD burner. IBM offers a 2-pound docking station that has a built-in optical drive, but carrying an extra piece does strain the shoulders. As an alternative, the HP 2710p's docking station is a lot lighter and also integrates a dual-layer DVD burner. Like the Fujitsu T2010, the T60 Tablet has three USB ports and one FireWire port, but it also adds mobile broadband. You can choose between Cingular's HSDPA and Verizon's EV-DO services, as indicated by the antenna bump on top of the screen.

I'm still scratching my head, wondering if I'll ever see a sub-4-pound convertible tablet with a standard-voltage processor. The ThinkPad T60 Tablet loads a low-voltage 1.6-GHz Intel Core 2 Duo L7500 CPU. It could be worse: You could be using an ultra-low-voltage processor like the ones found on the Fujitsu T2010, HP 2710p, and the Gateway C-120X. Even with 2GB of RAM, ULV processors have a tough time keeping up with Windows Vista. Over time, Vista will hog precious space and slow down your system. You can get away with a ULV processor by running Windows XP, but Microsoft will make you switch eventually. That said, the L7500 is a good choice if you want the best of both worlds: performance and battery life. If you don't mind the heft, the Fujitsu Lifebook T4210, the Toshiba Portégé M400, and the Gateway M285-E, with their Core 2 Duo T7000 series CPUs, can get you the power you need on a tablet, but there's a price to pay in battery life