Can I Connect Online Through Another CPU Using An NIC???

I Recently Built My Girlfriend A Computer But The Router Is Too Far Away From It To Get a Signal. Can I Somehow Network It Through My Computer? Her CPU Has A Belkin Card And Mine Has a Netgear. I Also Have A Old D-Link DWL-800AP+ Range Extender That Says It Can Be Used As an Access Point/Repeater. But When I Plug It Into My Computer My Card Loses Its Signal Completely. Both CPU’s Are Running XP Pro But Mine Has Ubuntu On It Also. Any Suggestions Would Be Greatly Appreciated.