Suggestions for Wifi adapters for a pc?

My brother just got my aunts old pc. We figured it's so old it cannot connect to wifi or bluetooth on its own. He needs some type of adapter that can help the pc connect to wifi, one that can be plugged into an USB port. Does anyone have suggestions for an affordable USB wifi adapter for pc? Are there adapters that can recieve both wifi and bluetooth connection? Neither of us know too much about this stuff so help is greatly apriciated. He has linux on it if that matters.