Wireless network adaptor?

the internet wifi on my laptop just broke so i need to buy wireless usb network adaptor, i watch alot of videos online and download stuff quite alot, so i was wondering what transfer speed would be enough for this, i was looking at the netgear n150 which has 150mbps transfer speed im not sure if this will be enough the next model up is the netgear n300 which is double the price but has double the speed. what would you suggest? my current laptop is a hp g56-130sa and im not sure what speed the internet wifi had but that seemed fine.