Wireless hotspot on my driveway literally

Hey guys there is a wireless hot spot which i am legally allowed to tap into which ic an acces on my phone wi-fi.

I want to try get the signal to my desktop pc which is 20 meters away from the poor signal inside.

I believe it is a G signal.

Is it possible to buy the wireless card + antenna to grab this signal?

Thanks guys i have no wireless gear atm so i need to buy it all.