Haven't heard about Helio yet? You're probably better off.
Helio is an MVNO (they use Sprint's Mobile Broadband Network) like ESPNMobile is/was, but with recently announced EVDO data service for $85/mo. They'd like you to believe that they are a good choice because they have a neat gimmick: a PC card that handles both EVDO and WiFi.
Their actual EVDO Service is likely to be as good as Sprint/Verizon, and will depend on coverage and connection strength.
So what's the problem with Helio?
Their version of "unlimited" bandwidth is only 160mb per month!
Outrageous really, since software updates can be that large all by themselves.
Lots of people are already dissing Helio... There are just too many unknowns -- like EVDO Rev-A compatibility, quality of support, and mostly... If these guys are even going to be around to see 2007!
You can read more about Helio's TOS and see what others have to say, right here:
Helio Offers EVDO Card, $85/month - EVDOforums.com