I use a Ralink. I bought it for 1.00 on Ebay. I bought a 10 foot USB extension cord and made a homemade parabolic antenna. (google it) If you do not need signal strength from across the street or a distance that USb antenna will do fine.
My Computer gets 4 bars and ranges from 48 to 56mbps the Max I can get. I get it free internet from the clubhouse across the street. If you own the router you are using. Consider moving the router and plugging direct into the RJ45, it is and always will be the fastest. My little antenna is a USB external and not even plugging into the Mobo.