AT&T's new HSPA network is the nation's speed king when it comes to cellular uploads and downloads (if you can find coverage, of course). The Option GT Ultra Express is a very convenient way for ExpressCard-laptop-toting road warriors to get in on the action.

The GT Ultra Express is a small card with a flip-up antenna, an external antenna port on the side, a SIM card slot in the middle, and mysteriously unlabeled red and blue activity lights. (Blue seems to be good.) To hit AT&T's network, you pop it into your laptop's ExpressCard slot (most newer notebooks have one) and load up either AT&T's free Connection Manager software for Windows or Option's GlobeTrotter Connect software for Mac OS X. During testing, both worked fine on a MacBook Pro running OS X 10.5.2 and Windows Vista under Boot Camp.

HSUPA (High-Speed Uplink Packet Access) is the latest upgrade to AT&T's network, and it isn't even officially live yet: The new technology will be rolling out over the next few months, according to AT&T spokesperson Warner May. HSUPA allows uploads ranging from 600 to 1,400 kilobits per second (1.4 Mbps), according to the company. It follows HSDPA 3.6 (High-Speed Downlink Packet Access, 3.6 megabits), which theoretically allows downloads up to 3.6 Mbps. In reality, we're talking downloads at around 1 Mbps. The Ultra Express actually supports HSDPA 7.2, an even faster variant of HSDPA that AT&T hasn't activated yet.

For the full history, HSDPA 3.6 followed HSDPA 1.8 (1.8 Mbps, which followed UMTS (384 Kbps), which followed EDGE (running at around 200 Kbps nowadays), which followed GPRS at a lowly 30 Kbps for average downloads.

Together, HSDPA and HSUPA make HSPA (high-speed packet access). HSPA is part of a family of technologies called "3G," or third-generation cellular. So when you hear "3G," this is what people are talking about.

AT&T's weakness is nationwide coverage. The company's HSPA network covers fewer U.S. metro areas than Sprint's or Verizon's competing EV-DO Rev A networks, causing AT&T devices to drop down to slow EDGE speeds when they're outside a 3G area. You can find AT&T's list of high-speed cities here. Be sure to check the coverage map before you sign up.

I tested the GT Ultra Express card in seven locations in California's Silicon Valley, comparing it with the Sierra Wireless USBConnect 881 modem. The results reflected the patchiness of AT&T's network: I got HSUPA in only two out of seven locations, and downloads were generally slower than I was accustomed to seeing on AT&T's network in New York City.

Where HSUPA was active, though, upload speeds got much faster. At the two HSUPA upload spots, I got speeds of up to 835 Kbps–more than double the 350 Kbps of non-HSUPA areas. This was slower than the USBConnect 881, but with so few data points I'm not willing to make a broad conclusion. Rather, I'll just say that HSUPA is fast.

Download speeds averaged 421 Kbps, dragged down by some slower results that may have been caused by Internet problems between AT&T and one of the FTP servers we use to test download speeds. Peak download speeds on a good HSDPA 3.6 tower were fast, though, at 1.6 Mbps. That's about equal to Verizon's peaks.

Like the USBConnect 881, the GT Ultra Express is tri-band HSDPA with quad-band EDGE, so it should work all around the world, including in Western Europe. But global travelers should watch their data usage, as AT&T's global data plan allows only 100MB per month of usage outside the U.S. before you start incurring high per-megabyte charges.

If you're confident you're going to have an ExpressCard laptop for a while, you can pop in the Option GT Ultra Express card and surf the Net at the best speeds AT&T will have to offer for at least the next two years or so. That's a fine option, but our Editors' Choice goes to the similarly performing Sierra Wireless USBConnect 881, simply because USB devices work with a wider range of PCs.