Now that we're seeing blazing speeds on Verizon Wireless's new LTE network, there's a pernicious misunderstanding going around on comment threads that I wanted to crush before it goes any further.

Theoretical maximum network speeds are not real-life speeds. T-Mobile's HSPA+ 21 will not get you 21 Mbps. Verizon's LTE will not get you 326.4Mbps, 70Mbps, or whatever you're reading out there. And Sprint/Clear's WiMax will not get you 40Mbps.

To the carriers' credit, they aren't promising these speeds. It's mostly coming from enthusiastic users conducting fanboy wars. Sorry, guys. T-Mobile's HSPA+ 21 is fast, but it's not as fast as Verizon's LTE, at least for now.

The actual speeds you see on real networks are dependent on a lot of things: how close you are to a tower, how many other people are using the tower, and the weather. (Seriously — speeds are lower in the rain.) The backhaul connection from your cell tower to the wired Internet is critically important; for the best speeds, you need fiber. The wireless frequency used affects building penetration, beyond the technology being used. Even the processor and OS of the device you're using comes into play. Our network analyst Samara Lynn gets faster network speeds on faster computers.

Yes, this means HSPA+ 21 in Australia may be faster than HSPA+ 21 here (I'm not saying it is, just that it's possible). The implementation of the network is even more important than the base technology.

Beyond that, the type of network traffic you're doing affects perceived speed. The high numbers we like to bandy around come from speedtest.net, which simulates streaming. I also do FTP and Web-download tests using the "curl" tool, and those speeds "appear" much slower on all connections.

The speed numbers that matter are what people are actually seeing live, on real devices. That's why organizations like Wired, PC World, Gizmodo and ourselves spend thousands of dollars sending people out for nationwide network speed tests. It's the only way to know.

We're seeing silly-fast speeds on Verizon's LTE network right now in part because it's only being used by a handful of journalists and Verizon employees. Think my 21Mbps was good? MSNBC's Wilson Rothman clocked 33Mbps in Seattle.

WiMax and HSPA+ are both, for now, slower.

I've tested WiMAX and HSPA+ each half a dozen times since they launched. This week in New York I got relatively slow speeds, so I'll give you more characteristic numbers. In Philadelphia in August, I got an average WiMAX speed of 3.8Mbps with a peak of 5.6Mbps; the fastest result any PCMagger has gotten was a 9.1Mbps in Atlanta. In New York in September with T-Mobile, the Rocket USB stick maxed out at 6.7Mbps. Yes, that's on an "HSPA+ 21" network, because "21" is the speed you get in a locked room with a giant antenna pointing directly at your head.

So do me a favor: if you want to quote speeds, show us a speedtest.net screen capture or something. Promises are just promises.