Dell Mini 9 With 3G (click for larger image)

Dell on Tuesday started giving U.S. buyers of its Inspiron Mini 9 mini-laptop the option of built-in mobile broadband from carrier AT&T.

The wireless wide area network support costs an additional $125, but users can get a $120 mail-in rebate from AT&T, if they sign up for two years of the telecommunications company's DataConnect Service plan. The option is available only with new Mini 9s running Windows XP. People with older models are out of luck.

The wireless support is provided by an Ericsson-designed 5530 HSPA internal minicard. The device supports download speeds of up to 7.2 Mbps and upload speeds of 2 Mbps.

The Mini 9 has been available with mobile broadband in Europe exclusively through Vodafone or directly from Dell. While the Dell netbook, which has a 9-inch display, comes with built-in Wi-Fi support, having access to mobile broadband makes it possible to get on the Web anywhere, rather than having to search for a Wi-Fi hotspot.

Dell launched the Mini 9 in September. Pricing in the United States starts at $399 with Windows XP and $349 with Ubuntu Linux. The system weighs 2.28 pounds, supports up to 1 GB of memory, and is available with a 4-GB, 8-GB, or 16-GB solid-state drive. The mini-PC is powered by a 1.6-GHz Intel Atom processor.

Dell includes 2 GB of online storage from Box.net at no charge. The system is available in multiple solid colors, as well as with artistic designs.

Mini-laptops are defined as sub-$500 lightweight PCs with screen sizes 10 inches or less. While limited in functionality, their size, ease of use, and low cost are expected to attract buyers looking for an ultraportable device for e-mail and Web surfing on the road.