What is the USB modem, is it 3G as well? If you are comparing USB 3G cards and PCMCIA 3G cards, I would go USB for a few reasons. One, most of them install their own drivers when you plug them in. Two, you can use them on any computer, where the PCMCIA card requires a PCMCIA interface. Three you can buy a USB extension cable and put the card in a higher area where you have better reception.