about to try the 30/month t-mobile basic plan.
got a GSM motorola atrix HD on the way. this seems to support teh 4g t mobile bands.

the plan is to use VOIP with google voice and pbxes.org to make phone calls via data.

I had tried this with my sprint, and the result was OK. driving, handoffs would cause a but of voice drop, and wifi was spotty in some places at home.  I fixed that by taking a router and programming it with DD-WRT and making a repeater.