i have an ExpressCard Merlyn EX720 from Sprint that i got through my work. It works great with MPB, no drivers of any kind needed, but it is slooooooooooooooooooow. It works in some retarded areas where other phones don't but its still kinda sketchy.
I moved couple of weeks ago and wasn't able to locate the card in a pile of my things, so i decided to try tethering with my AT&T iPhone 3GS. That thing was FAST. I downloaded 2 230Mb Entourage episodes from BitTorrent in about 15 minutes.
So yeah, 3GS with Tethering on AT&T gets my vote.
Oh, i also used to have a Verizon card. That was the biggest piece of shit i have ever seen. I could barely achieve 56k speeds in town. Outside of town? Forget about it.
this thing looks kinda cool though
http://www.engadgetmobile.com/2009/0...i-2200-review/