@Original Poster
Data cards use the CDMA network for all data uploads/downloads.
Data card maybe of three types;
1. USB Plug-in : Goes into the USB port.
2. PCMCIA Card : Goes into the PCMCIA Slot on your Lappy. View the manual to know if you have one and where it is located.
3. Expresscard type : Like PCMCIA card but different slot.
The easiest and most versatile will be USB one, as you can use it in any laptop, desktop, as all have USB in them.
@Bandu
What you are talking about is Wireless LAN, The poster mentions about Data cards and wireless Internet. Lan and Internet are actually very different things.