Wireless connection dropping in speed

[PureAppleJuice]

Hi there, basically on this crummy replacement USB wifi dongle I bought the signal is at 80% roughly yet once I connect to the network the speed just slowly drops from 54mbps to 11mbps, if not 5.5mbps.

Any idea at all why it is doing this? Conflicting networks perhaps? It's the Netgear WG111 'v3'.