Don’t kid yourself: Fujitsu’s tiny Lifebook U810 isn’t about to replace your notebook computer any time soon, and it won’t make you chuck your BlackBerry or Treo into the trash. But the $999 U810 may fill a niche for many mobile Web surfers and on-the-go executives.

Surprisingly, Fujitsu’s tiny tablet PC is loaded with features that rival larger notebook computers. Users will find 802.11a/b/g, Bluetooth, wireless broadband (AT&T), Webcam, a 40GB hard drive and a fingerprint scanner all crammed into the 1.5-pound device.  Measuring just 6.73 inches wide, 5.24 inches deep and 1.04 inches high, the U810 also offers a 5.6-inch WSVGA (1024-by-600) touch-screen that swivels and converts the diminutive unit into a small tablet PC. For those looking to play with the unit as a mini-tablet, a tablet pen is hidden in the display lid.

Check out pics of the Lifebook U810 in our slide show.

The unit is powered by the Intel Ultra Mobile Platform 2007, which consists of an Intel A110 processor, 945GU Express Chipset and an Intel ICH7U I/O controller hub. Video is handled by an Integrated Intel 3-D Graphics Accelerator, while 1GB of DDR2 RAM rounds out the equation. Built-in audio is based upon a RealTek ALC262, which is connected to a single internal speaker and integrated digital microphone. Surprisingly, the tiny U810 offers several ports, including  Audio-in, Audio-out, Type I/II CF Card slot, SD (Secure Digital) Card Reader and a connector for a USB 2.0, 10/100 Ethernet and external VGA combo adaptor. For those looking to use the U810 more than just on the run, a docking station is a welcome option that can transform the tiny PC into a desktop computer, albeit a slow one.

Speaking of performance, the U810 was able to muster an overall score of 146.2 using PassMark’s Performance Test 6.1. Not too shabby considering the small size and price point of the unit. Battery life ran about 3 to 5 hours, depending on the options in use. Constant use of the integrated wireless broadband seemed to drain the battery a little quicker than using the integrated Wi-Fi. The Bluetooth radio also sucked up the watts, impacting battery life some more. The basic rule of thumb here is to shut off all unneeded options to get five hours of computing from the four-cell 5200mAh Lithium Ion battery pack.

Our test sample came with Windows XP Tablet edition installed, but Fujitsu does offer the option of Windows Vista Basic edition. Most users will want to stick with XP for as long as it remains available; we can’t see how anyone would be satisfied with the U810’s performance running under Vista. With XP, the U810 was amazingly snappy and proved to be very usable from a performance standpoint.

Speaking of usability, what can one actually use the unit for? Well, right off the bat, the unit does browse the Web significantly better than most PDA counterparts on the market. Also, the ability to run Microsoft Office makes the unit a quick and handy tool for e-mail, PowerPoint presentations and even typing up a document or two, although you may sprain your thumbs typing. Thumbs? That’s right, even though the unit has a keyboard bigger than any PDA on the market, those with bigger hands are going to find thumb typing the way to go. Touch typists need not apply!

Mousing around is another issue. The unit features a touch-sensitive pointing stick, which takes a lot of getting used to and may be difficult to master. Although it is better than nothing, there is some room for improvement here, and users may want to forgo the default pointer and just use the digitizer pen to select icons. Switching over to tablet mode takes little more than flipping the screen around; the U810 handles the rest by changing the screen orientation and offering the XP tablet features automatically. The digitizer pen works well in tablet mode but can be a little oversensitive. That is in part due to the high resolution used on the small 5.6-inch screen.

That brings up another point: While having WSVGA resolution is great for cramming a lot of information on the screen, there are those users who may just find the text and icons too small. The unit does offer a magnify option, but when in use, less screen real estate is available. Considering that there is no viable solution to that particular problem, Fujitsu has done a great job compromising on the resolution/screen size conundrum.

So, the question still remains: What exactly will this unit replace in the knowledge worker’s briefcase? Probably nothing. It doesn’t offer an integrated cell phone, so it won’t be replacing that common business tool, and the overall form factor is too small to really replace the ubiquitous notebook computer. But the unit does do a great job at performing some minor tasks, such as e-mail, slide shows and surfing the Web. What’s more, with the wireless broadband connectivity and integrated Webcam, the unit could make a great little video conference call system for those using Skype or other VOIP (voice over IP) technologies. What’s more, the ability to run a standard version of Windows (XP in this case) means that the system can readily be configured to connect via corporate VPNs, terminal server clients and most any other traditional Windows connectivity product, which may make the U810 a great tool for the traveling salesman or tech support guru. While it’s far from perfect and there are plenty of nits to pick, the U810 proves to be a unique solution for mobile professionals and niche markets, and you can’t deny that the unit is just plain cool!