3G Mobile Card Problem

My son has a netbook that came with a Mobile Broadband deal where he was given a dongle and a sim card to go with. To save up one USB, he has a slot behind his battery where he can put a sim card in to access the internet. He didn't know what this was at first but he put the sim card in and tried to connect to the internet and it worked. I thought this was great and wanted to do this on my laptop. It's a Dell Latitude E6400 and it has the same slot for a sim card. I too have mobile broadband so I went and bought a mobile card which I installed into the laptop. But I can't seem to get it to work like my son did. I really don't know much about what I'm doing here but my basic question is, how can I get to do what my son does, on my laptop? Any help is appreciated.

Thanks

Yeah I've done that. Still nothing.

I've been on the DRiver section before, what specific driver do you suggest I download?

Oh, well I know I've got a 5520 card, that's all I really know.

Ok I'll try these. I'll be back in 5.