Without knowing what you mean by a gateway and an adapter/antenna assembly, I can only say that if they constitute a USB powered wireless dongle, that's all you need. A PCI card is not necessary if you have the right kind of USB wireless adapter. When those adapters are plugged in, the wireless icon should show up and you are offered networks to join. Put in the security key and you should be connected.
Thank you soo much! Yes, I think it's a dongle, but I don't have it yet. I just ordered it yesterday and will be here on the 10th. It's a 'Premiertek PowerLink Wireless 802.11b/g/n USB 2.0 Adapter' so that is a 'dongle', correct? I know soo little and am trying to learn. My laptop hooks up automatically so it must have a card inside it as I don't need a dongle for it. The gateway as the company calls it also has my phone hooked into it rather than just a router.