I'm thinking about getting an unlocked Windows Phone 7 and using prepaid wireless with it. 1) Is it possible to get a data plan without a contract (e.g. Verizon?) 2) Is there a way to get GPS navigation on a Windows Phone 7 with prepaid wireless from T-Mobile? (I don't mind buying the map data.) 3) In a nutshell, what is the difference between a data plan and WiFi? (Aside from the fact that you have to pay for a data plan.) Thank you very much in advance!