If you don't have broadband yet start pricing ISP's. Most will supply you with a wireless router/modem and you then have to add a wireless adapter to your laptop -- PCMCIA or USB.
If by cable you mean ethernet -- you can add a network socket -- USB or PCMCIA.
My biggest concern, is not tying up my phone line while I'm online. The computer I'm getting has a USB, and a PCMCIA. It is a refurbished DEll C610. Forgive my ignorance, but I really don't know what to do. Thanks for your help.