Best Option
I don't have a broadband card, I just have a Sprint Pocket PC.. Connects the laptop consistantly at DSL speeds for free except for the weakest of signals. The broadband cards are nothing more than a gimick to rape you for more money.
Most 3G phones, contrary to what Sprint or some other service will tell you, DO act as modems. Quite good ones at that. My phone came out of the box with the capability. Nothing extra to buy. This is not the case with some of the cheaper phones, you will have to buy a $30 USB kit for your phone.
Under my plan because I have unlimited vision for $10/mo I pay NOTHING extra and have great service. Some of the older 3G phones have some quirks with them and run about 125kbps, but it is still worth it for the price.
Verizon phones work the same way as well from what I understand. I have never used it, but I have seen the kits out there for them.
You can go to futuredial.com to find the kits for your phone or just visit the local Radio Shack.