As I mentioned yesterday, I'm one of Sprint's early Xohm WiMax customers in Baltimore. Today, I took WiMax out for a test drive across town. Literally. The verdict: Fast, but spotty.

First, the installation. Set-up is simple, just as it is with the home modem. I loaded the software, plugged in the ExpressCard, and got going. Since I don't have an ExpressCard slot on my computer, I had to use the PCMIA adapter that came with the ExpressCard. Once connected, I was taken to a Web site where I was prompted to add my new device to my account, and voila, I was up and running.

This afternoon, I decided to take Xohm to task. One of the promises of mobile WiMax, we've always heard, is that you can take it anywhere with you, and wherever there's coverage, you'll be connected at pretty blazing speeds. That means even while driving quickly, turning corners, and in stop-and-go traffic.

When I was connected, everything seemed great. I got anywhere from 2.1 Mbps for downloads between big buildings downtown to 5.5 Mbps driving through a neighborhood, 840 kbps to 1.4 Mbps uploads, and about 100 ms latency in several speed tests. I was able to watch The Simpsons in hi-res (480p) on full-screen mode without much jitter at all and no rebuffering, despite the fact that my wife was driving at about 35 mph. Multiple Web pages easily loaded at once while a live soccer game streamed on Ustream. Multiple simultaneous YouTube streams and The Simpsons all together were no problem.

Overall, I was very pleased with the browsing and viewing experience, which compared favorably with my Wi-Fi performance when I'm sitting in the living room, one floor and several rooms away from the five-year-old wireless router that's connected through Comcast, and seems much better than my old Verizon 1xEVDO card.

But that's just the "fast" part of my verdict. Unfortunately, during a drive across town and back, I lost connection several times, even though I never crossed outside of the coverage area, according to Sprint's "Coverage Tracker" Web site. The computer also experienced repeated trouble re-connecting when it again found the network, and I couldn't tell why.

This is something Sprint will have to get worked out if local delivery businesses intend to use the network for work, or if parents intend to drive around while kids stream movies from Netflix in the backseat of the van.