The MacBook Air may have set the bar, but these new ultrabooks raise it, packing features into an ultrathin package. These four models run Windows 7 and have a speedy processor, 4GB of RAM, and a webcam. Which is the ultra-est?

HP Envy14 Spectre

At 3.9 pounds, this 14-inch ultrabook is heavy, but it does a lot. You can connect wirelessly to an HDTV or projector with an adapter and use near-field communication, or NFC, to transfer URLs from an NFC-enabled smartphone. The Gorilla Glass display, lid, and palm rest are durable, if slippery. Bootup took 20 seconds; copying a 250MB file to a thumb drive took 23 seconds. The keyboard sagged a bit, but audio was the best of the bunch. The battery lasts up to nine hours on a charge.
Cost: $1,400

Acer Aspire S5

With the best performance benchmarks in our tests, the 13.3-inch S5 is our top pick. It weighs just 2.9 pounds, the same as the 13-inch MacBook Air, and it's an even slimmer 0.59 inches thick. A port panel on the back opens with the touch of a button, revealing two USB ports, an HDMI port, and a Thunderbolt port. The S5 boots up in 15 seconds and takes just 21 seconds to export a 250GB file. The keyboard sagged slightly, and audio was thin, but the only real sour note is the 6.5-hour battery life.

Samsung Series 5 ULTRA

The 14-inch Series 5 has an unusual perk for an ultrabook-an optical drive for playing DVDs and burning CDs. Unlike the other models we tested, it uses a 500GB hard drive instead of a lighter solid-state drive. Still, at 3.9 pounds, it is the same weight as the HP Envy, which has no optical drive. Bootup took 20 seconds, as did ripping a 250MB file to a thumb drive. The rigid keyboard was great for fast typing, but battery life suffers for the optical drive; it lasts just about seven hours on a charge.

Dell XPS 13

This 13.3-inch Dell really stands out for its top-notch display. At 2.99 pounds, the XPS is just a bit heavier than the Acer S5. It's also a hair thicker, at .71 inches, but its 12.4-inch width (displays are measured diagonally) gives it a slightly more compact profile. The keyboard is rigid, and video playback quality was the best in our tests, with rich, realistic colors. Bootup time is 16 seconds, and copying a 250MB file to a thumb drive took 22 seconds. The battery caps out at about nine hours.