Spearheaded by chipmaker Intel, Ultrabooks are Windows PC manufacturers' response to Apple's popular MacBook Air, a slim-and-light laptop that replaced the venerable hard disk with solid state (SSD) storage, and eliminated the seldom-used DVD drive altogether.

The Ultrabook strategy appears to be working, at least for Dell. Sales of the XPS 13, which debuted at the end of February, are twice what the company had originally forecast, Dell product marketing director Alison Gardner tells .

Dell has refocused its efforts on the enterprise market in recent years, and nearly half of the XPS 13 sales have been to corporations, Gardner says. The company declined to provide Reuters with exact sales figures.

The XPS 13 fared well in a recent , earning 4.5 out of 5 stars. "Compared to what we're used to seeing from Dell, it's a design marvel: thin, light, sleek, and well built with high-quality materials," wrote reviewer Jason Cross, who did find fault with the laptop's "disappointing display quality."

PC vendors are expected to ship many more Ultrabooks this year, with prices starting as low as $699, according to Intel. Some analysts believe Ultrabooks will from tablets, which may be better suited to consumer and corporate users with basic computing needs.