2G verus 3G iPhone?

Hey, I wasn't sure if I should post this here or in the Hardware discussion forum... so I just put it here...

Anyway, I wanted to get an iPhone. I currently have T-mobile, so obviously I'm going to need to get a jailbroken one. I was wondering what Wifi speed advantages there are with 3G over 2G. That will be my primary use, aside from texting/calling. On Craigslist, 3G is a bit more expensive than 2G, so I'm reluctant to spend more money unless it is definitely worth it.

3G is much much faster than 2G/EDGE. I'd go with the 3G if your a heavy data user.