If you have a wireless router that can accept 3G models that is one thing. Otherwise, I would do some reasearch into whether you want to be sitting 6 inches away from your laptop with a cellular receiver on - and radiating - for extended periods of time.

This is something that people havent throught about much but with your phone you have it on briefly, not the long periods that you would be exposed if the 3G card is the only internet connection you have.

But if you can move that receiver a bit futher away via a modem, maybe that is a bit safer.

No one will really know about this for a long time, but you dont want to be on the wrong side of the answer.