The 5760 has what is known as the express card slot. this is narrower than the older pcmcia card. The express card is new technology, unfortunately there are not that many items on the market for this.
I have recently had to purchase from verizon a new broadband card. Since I was not eligible for an upgrade it cost me full price $300.00. Also since it is the first one offered they can charge what they want since the demand right now is greater than supply.