The busiest intersection in laptop computing is that where price and performance—or, if you prefer, PCMag's budget and desktop replacement categories—meet. Call it the mid-market zone, and call the Asus K53SD-DS51 ($779.99 street) the latest competitor: a newly refreshed 15.6-inch model that packs several appealing features, but not enough to unseat our reigning Editors' Choice.

Compared with the K53E-RBR4 model tested here in October 2011, the K53SD-DS51 adds the USB 3.0 port that was missing, steps up from a roomy 640GB to an even roomier 750GB hard drive, and adds muscle in the form of an Intel Core i5 rather than i3 processor and Nvidia discrete graphics. On the minus side, it lacks Intel's increasingly popular Wireless Display (WiDi) for zapping video and audio to a suitably receiver-equipped HDTV set. Nor will you find Bluetooth for syncing your laptop and handheld—both features found in competitors such as the Acer Aspire TimelineX 5830TG-6614 ($779.99 list, 4 stars) and Lenovo IdeaPad Z570-10249ZU ($699.99 list, 3.5 stars).

Design
The K53SD-DS51 features an attractively etched or cross-hatched, smudge-resistant lid in mocha—a rich brown with a hint of bronze—and scratch-resistant gray aluminum palm rest. Weighing 5.75 pounds and measuring 10 by 15 by 1.4 inches (HWD), it's a fraction bigger and heavier than the average 15.6-inch notebook but still fairly portable.

Like most of its competitors', the K53SD-DS51's keyboard makes room for a numeric keypad on the right side, with slightly narrower keys than the main keyboard area. The keypad offers dedicated Home, End, PgUp, and PgDn keys, though media functions such as play/pause, stop, and volume control are doubled up on the cursor arrows and function keys instead of getting their own keys. Typing feel is quite comfortable, as is the smooth, almost slick touchpad with its twin clicky mouse buttons.

The glossy 15.6-inch display offers the 1,366-by-768 resolution that's standard fare in this segment, sufficient for watching 720p videos or putting a couple of application windows side by side. It's nicely bright and sharp. Audio through the Altec Lansing speaker bar above the keyboard is good, though not particularly loud.

Features
As mentioned, though the 802.11n Wi-Fi worked fine for Web surfing, we were disappointed not to find the Wireless Display technology available on comparable machines and our budget Editors' Choice Asus U56E-BBL6. Wondering if it was just a matter of missing WiDi software as on the Toshiba Portege Z830-S8302, we visited Intel's site and downloaded the utility, but got a "This platform is not compatible with Intel WiDi" message when we tried installing it.

On the K53SD-DS51's right side are headphone and microphone jacks, two USB 2.0 ports, and the dual-layer DVD±RW drive. An MMC/SD/MS memory-card slot is on the front bezel. On the left side you'll find Ethernet, VGA, HDMI, and USB 3.0 ports—and the AC adapter connector, which is oddly mounted amidships instead of being relegated to a rear corner as with most laptops.

The 750GB, 5,400 rpm hard drive has room enough to hold your documents and digital media for years to come. It's divided into 293GB C: and 380GB D: partitions plus a hidden recovery partition. The drive is also fairly free of bloatware, unless you count a Trend Micro Titanium Internet Security trial as bloatware; preinstalled applications include Microsoft Office 2010 Starter and CyberLink's Media Suite for the DVD burner.

Asus earns points for the laptop's warranty, which lasts two years instead of the usual one and includes one year of accidental damage protection.

Performance
The K53SD-DS51 combines Intel's Core i5-2450M, a dual-core, four-thread CPU that runs at 2.5GHz, with 6GB of DDR3 RAM and Nvidia GeForce 610M graphics with 2GB of memory (a combination once reserved strictly for exotic gaming rigs instead of midpriced laptops). An "instant on" feature changes the default power button function and Windows Start menu option from shutdown to sleep and enables wake from sleep in about four seconds.