evdo stands for "evolution data only." umts stands for "Universal Mobile Telecommunications System." Neither of these terms mean anything but they do sound impressive. They are basically both the third generation of cellular data transmission standards. Every generation gets about 10 times faster then the last generation.

(i get more technical as i go along so skip down if you get bored)

The previous generations were named 1xRTT and EDGE respectively for about a 100kbps. Before that there was Quick 2 Net and GPRS at about 10kbps-ish.

So, back to now. Pros of evdo is that Verizonwireless is offering it. It has a larger coverage area than ATT's umts does. Yes, I realize that evdo is only supposed to be in 3 cities but trust me - it has a larger footprint. It is also faster. With the optimal tuning of your system and venturi software going full blast, you'll get about 1000kbps.

Ah yes. I almost forgot to mention, evdo is backward compatible to 2.5 generation 1xRTT. BUT, umts is NOT downwardly compatible to EDGE. umts only synchs down to gprs.

As far as the pros of umts, there are many. First of all, it is in 6 cities. Second, while it delivers slower speeds at about 200kbps, your umts end user experience can feel like evdo PARTIALLY due to data transmission gap times SOMETIMES being tighter. Guys with degrees call this latency. The biggest advantage of umts is that you can use your u520 card in europe, asia, and south america (so i've been told... personally not tested).

Suffice it to say that surfing between different websites will feel quick using umts while evdo will present more of a lag time. But, when you are doing a download from just one site, evdo will hit harder.

So if i had to put myself in your shoes, I'd look at which cities i travel to most. Then compare that list of cities with the evdo and umts coverage map to pick which service I elect. Secondary factors would include your websurfing frequency vs. straight up / downloading and which carrier you still own shares of. (did i just end my article on a dangling participle?)

Lets Talk: Welcome to the EVDO Chat Room (if i am online)