I have a T-mobile Shadow 2007 with unlimited text and internet for $19.95. My phone just broke so I need a new one. Will a different phone work with the Shadow plan for internet? Would a 3G phone work?

I don't really want to pay the $34.99 they want for phones like the G1 and I dont see why I wouldn't be able to go online if i just switch the sim card. 20 bucks for unlimited text and internet is a great deal!