It’s easy to be seduced by Alienware’s m15x notebook. From its handsome silver-gray case to its cool-yet-tasteful LED accents to its comfortable lap weight of less than eight pounds, this 15.4-inch machine had us at hello. Of course, only excellent performance would keep us interested.

Our hopes were high. The m15x came to us sporting Intel’s new 2.8GHz Core 2 Extreme X9000 mobile CPU and Nvidia’s GeForce 8800M GTX videocard. Those are the highest performing mobile parts in their respective categories—a caliber typically reserved for larger, heavier 17-inch models.

For comparison’s sake, we turned to the Asus C90S notebook we reviewed in October 2007, rerunning all of our notebook benchmarks on Vista. The C90S is unique in that it uses Intel’s Core 2 Duo E6700 desktop CPU. Clocked at 2.66GHz on a 1,066MHz front-side bus, the E6700 seemed like a worthy competitor to the X9000 mobile part, which has a modest 140GHz clock-speed advantage but a slower 800MHz front-side bus.

Turns out, however, the fight wasn’t really all that fair. The X9000 part has the benefit of Intel’s 45nm Penryn core, as well as 6MB of L2 cache (compared with the 4MB found in the E6700), and apparently that makes all the difference. In our CPU-dependent benchmarks, the m15x performed 11 percent to 31 percent faster than the C90S.

The two notebooks were divided even further by our gaming benchmarks. The m15x’s 8800M GTX walloped the C90S’s 8600M GT, most dramatically in Quake 4, where it did 178 percent better.

When this type of all-out graphics power isn’t needed, you can reboot and switch from the videocard to the chipset’s integrated graphics to preserve battery power. It’s a nifty idea, but in our own battery rundown test—playing a standard-def DVD until power is depleted—we gained just nine additional minutes using the integrated graphics (for a total of one hour and 35 minutes). The m15x also offers a Stealth mode, which lets you throttle back the CPU and GPU for power savings and quieter operation.

The m15x came to us with a 200GB 7,200rpm hard drive and a Blu-ray burner, but the latter can be easily popped out of its Smart Bay and hot-swapped with an optional 320GB 5,400rpm secondary drive ($300) or secondary battery ($150).

In another nod to customization, a software Command Center lets you change the colors of the m15x’s various LED lights, making the power button glow red, for instance, while the keyboard backlighting glows green and the illuminated piping around the notebook’s lid glows blue. A row of touch-sensitive buttons above the keyboard contributes to the m15x’s light show, but while they look cool, they’re not especially reliable—we sometimes had to press them several times to get a response.

We have no complaints, however, about the m15x’s 1920x1200 screen, which offers a 1920x1080 option for use with high-def content. Available ports consist of three USB ports, a FireWire port, HDMI, Ethernet, and mic. Sadly, no eSATA.

In the end, our infatuation with the m15x remains strong. It’s as powerful as any 17-inch notebook out there and much easier to carry around. And it looks good, to boot. Consider us sold—even if the price does break us.