We also use Verizon to dial up the Internet while traveling. It is slow but better than nothing. We bought the cable and a phone that can be used as a modem hooked to the laptop. We did not have to buy a larger plan but we aren't on the most basic plan either. One must certainly make sure you are not roaming and have good strong signal before connecting. We were not able to get the software and found out after talking to a Verizon cust. ser. rep. on the phone we did not need it. He helped us create the connection. We use MSN Explorer to collect our hotmail account and do our web searches. It all works very well.
The newest deal Verizon and other companies have with true high speed available only in certain areas is faster but much more expensive. The only cost we have with Verizon is the phone service and the cost of the phone & cable.
If you add a WiFi card you will increase your speed when in an area where you can find the signal.