when I said "detail"
what I actually meant was provide specific details of the wireless cards you have.
"a PCI D-Link card, However It is too big to even fit inside the Desktop."
from that I assume you currently have no network card in your desktop
So in answer to your question, yes you will need to buy a wireless card/device.
I have used an Alfa AWUS036H in the past, it is USB and does all the fun stuff.
if you are going shopping, start here