Does anyone know if it is possible to use the SIM from a contract iPhone 3G in a computer network card.

I am looking at getting a Merlin XU870 HSDPA Expresscard to connect to the internet using my Macbook pro. I currently have an iPhone 3G on a o2 contract and was wondering if I can use the SIM from the phone in the expresscard. As the contract gives unlimited data I was hoping I would be able to use this with the computer via this card.

Obviously the contracts are different in the UK to the USA.