I've been looking on Wikipedia to try and figure this out, but I'm not much closer.

As far as I can tell, GSM is for overseas only?

What is the difference in speeds between EDGE, EVDO, CDMA, GPRS? Are they even the same thing?

I'm trying to decide whether to get a BB 8310 or a BB 8830. I use Sprint, and they don't offer me a 8310, so I'd have to change carriers and pay penalty.

Is the 8830 plenty fast? I don't plan on streaming video and such. I just want to browse the internet and IM/Text.

errrrr... AT&T and TMoUS are both GSM networks (overseas if yoe in Europe ;?).
Roughly speaking: AT&T and TMo are GSM networks, using EDGE.
Verizon and Sprint are CDMA networks, using EVDO.

EVDO is faster the EDGE

BlackBerry Glossary - BlackBerryFAQ

Thank you very much. This has helped me more than 3 days of searching!

Moved to General Blackberry Discussion Forum.

Worry about your carrier's coverage first -- device/network tech second.

The fastest device out there won't do you any good if it doesn't have coverage.

Sprint doesn't offer the 8310 because they're CDMA. The 8330 will be their equivalent.

The 8830 (EVDO) should be faster than the 8310 (EDGE). Which features are you looking for? Can you wait for Sprint to release the 8330 if the 8310's features seem more appealing to you than the 8830?

hi john, i have blackeberry telcel..ist possible to converted to us carriers like at@t or t-mobile,,flashing or something else.....ty

Yes, you can. You need to have the Blackberry unlocked, though. Contact Horizon Wireless for unlocking.