Network provider

[Guest dufunkus]

I have a brand new unlocked Streak with an AT&T sim card in it, from my old lg vu. All I have is just the calling plan. I want to get a no contract unlimited plan to get online, etc., since I now have this beautiful new phone. Which carriers, network providers, can I use and which are the cheapest? AT&T's data plan seems too pricy. Thanx, in advance, for the help...