Your notebook means business in every sense of the word. The problem is, not everyone defines their work style the same way. Busy professionals crave an equally agile, lightweight laptop to fit their life in motion. Others need the brute force (and huge screens) that only a desktop replacement "portable" can provide. Then there is everyone else--people who want to combine reasonable power with the flexibility to go anywhere.

Most of us, though, no matter which kind of machine we favor, want to find that Zen state of great mobile performance and better battery life.

That's exactly what we're aiming to do here. Pouring over reams of data on products in our three laptop categories--namely, ultraportable, all-purpose, and power--we've sifted out our choice in each category for notebooks that offer the best balance of performance and endurance. Everything else is secondary. That means that money is not an object in this search for the best workhorse computers--although the reasonableness of the prices for two of our winning models will likely catch your attention.

It's hardly a surprise that one of the more recent desktop replacement laptops to enter the Test Center wins out as the best choice. The Micro Express IFL9025 is one of the first Penryn-processor-loaded notebooks to roll off a factory line and into our offices.

The IFL9025 comes fairly well stacked with the hardware to garner high scores on our WorldBench 6 tests. Intel's 45-nanometer-based processor leads the charge with a 2.5-GHz Core 2 Duo T9300. This CPU, while not the fastest member of the Penryn family, had more than enough to handle any business task we could throw at the machine, delivering a downright impressive WorldBench 6 score of 97, tying it with Eurocom's D900C Phantom-X and just edging out Toshiba's high-end multimedia Qosmio G45-AV690 (which scored a 94). (Both are comparable desktop replacement machines.)

Besides business productivity, the other big reason to consider buying a desktop replacement is for its game-playing ability. The IFL9025, however, doesn't pack the most powerful 3D punch. It relies upon an nVidia GeForce 8600M GT video card with 512MB of dedicated memory. That's more than potent enough for games such as Far Cry that have kicked around for four years (the IFL9025 cracked 120 frames per second--a good score for an aging title such as Far Cry), while also being capable of dealing with what's on the store shelves today. Just don't expect to play games such as Crysis at top resolutions with all features cranked to "11." Gaming on most notebook computers entails a series of compromises. So tone down your expectations and keep the antialiasing features off.

All this said, we still have a stack of notebooks that haven't yet finished running the WorldBench gauntlet. One model in particular stands will likely best the IFL9025 in gaming performance: Alienware's Area-51M m15x. This notebook truly feels like a desktop replacement in that, besides having 4GB of RAM and a Penryn CPU, it uses two 8800m GTX graphics cards in Scalable Link Interface mode (SLI). That's right, a notebook that is brawnier than your average gaming desktop--no small feat.

As for battery life, one again needs to keep expectations in check with this sort of machine, as these PCs sponge power--and the longest we've seen a desktop replacement run on one charge is a little over 4 hours. Micro Express's IFL9025, however, is a close second in this respect, coming in at 3 hours, 53 minutes--about 12 minutes longer than the average for all desktop replacements.

What caught me off-guard, though, was how inexpensive (at $1199) the IFL9025 is, considering how absurdly costly desktop replacement portables can be. Price may not be a factor in this story, but it's nevertheless hard to ignore a good deal when you see one.

All-Purpose: Sony VAIO VGN-SZ791N

A not-quite-ultraportable notebook, Sony's VAIO VGN-SZ791N is really a "tweener." It has the size and weight of a borderline ultraportable (it weighs 4 pounds and has a 13.3-inch screen), but this laptop is a racehorse at the track, and it is built for business.

In fact, when it comes to straight sprints in WorldBench 6, Sony's VGN-SZ791N is unstoppable. Scoring 94, it outran the nearest-performing all-purpose notebook, Fujitsu's Lifebook A6120, by a full 10 percent--and kept pace as well with beefier desktop replacement models. This is thanks in no small part to the combo of an Intel 2.5-GHz Core 2 Duo T9300 CPU and an nVidia 8400GS GPU revving under the hood. If you're paying close attention, you may have noticed that Sony takes the same Penryn-based CPU of our top desktop replacement pick and fine-tunes it for this more mobile unit.

As for battery life, the SZ791N doesn't quite achieve a runaway success, but it does last 3 hours, 50 minutes on a single charge. That's slightly better than the average all-purpose notebook. A power management toggle on the keyboard switches between a Speed and a Stamina mode; I assumed that this would add more borrowed time to work with, but it didn't do much. Besides throttling down the CPU, this one-step "solution" tweaks a couple features (like lowering the resolution) and forces the computer to reboot. I couldn't help but wonder how much power was killed jumping through all those hoops in the first place.

A couple of notebooks have managed to squeeze out more juice than the SZ791N, but by far the most long-lasting laptop among all-purpose models we've tested recently is HP's Pavilion dv2660se. It's a true marathoner, cranking away for 6 hours, 19 minutes on the 12-cell extended-life battery it ships with. However, this Pavilion didn't walk away with the top spot because its CPU dragged it below the average of other all-purpose laptops' scores in our WorldBench 6 tests.

Among the "money is no object" set, the Sony VAIO VGN-SZ791N will make a solid choice. It may cost $2500, but this pint-sized powerhouse can run circles around the competition for nearly 4 hours.

Ultraportables make all sorts of sacrifices-such as accepting anemic CPUs-in order to break into the welterweight computing class. Not Lenovo's ThinkPad line. Durable, svelte, and geared up for business, these PCs perform under pressure. In fact, a number of Lenovo's notebooks regularly creep into the Top 10 in the ultraportable category.

The ThinkPad X61 isn't the fastest notebook you can find, but thanks to a Santa Rosa class Intel CPU (a 2-GHz Core 2 Duo T7300), it still managed to crack the top four in our WorldBench 6 test suite, scoring 75-not too shabby for an ultraportable machine; it comes in close behind the Lenovo 3000 N200 and Dell's more potent XPS M1330. The only ultraportable that scores better, the Micro Express JFT2500, blows away the X61 by a huge 17 percent margin.

The problem is that there's a wide gap between ultraportable performance and endurance. Every machine that clocked a high score in performance fared miserably in battery tests-and vice versa. For example, the JFT2500--the fastest ultraportable we've tested--sits nowhere near the top of the battery-life pack. That honor goes to the ASUS U2E, which ships with both a standard and a 6-cell extra-life battery that lasts an absurd 7 hours, 11 minutes in our tests. The ThinkPad X61 also comes with an extended-life power supply, but it runs about an hour less than the U2E by comparison (6 hours, 14 minutes, to be precise). Still, 6 hours is a good amount of time to survive our battery stress tests.

However, as I said from the beginning, this month's quest is for that best middle ground, and the X61 delivers in spades as a well-rounded machine in its category. It's aging a little (it came to market last year), but you can't argue with the X61's success. And considering that this tricked-out 12.1-inch portable notebook line starts at a little over $1000, it also happens to offer a lot for your money.

--Darren Gladstone