I'm looking into a data plan from a carrier in the US for use with my MBP. I've researched the rates for the carriers in my area (Verizon, Sprint, AT&T, and T-Mobile). T-Mobile is the cheapest, but all I can find from them is a PCMCIA card. Is there a USB or ExpressCard compatible card available through T-Mobile? I know Verizon has those, but the service where I'm needing it isn't great. Does anyone have any experience with these plans?