There is much hype made about using an internal modem, but after using the d-link internal modem for over an year now, I have found nothing unusual or awkward about it. An internal modem works exactly the same the way as an external modem and there is no difference in the data transfer speed or connectivity. The only difference that is there between these two is that you cannot switch off an internal modern, a drawback that comes under consideration only when there is bad weather outside.
The sole risk in using an internal modem is that whenever there are the voltage fluctuations there is a chance of damaging the computer due to the fluctuations. But practically speaking, the slightest chance of this thing to happen is when you use the modem even when it is raining and lightning outside. So, in my case I just avoid using the modern in such conditions thereby saving almost 50 percent of the money.