The smallest USB WiFi Network Adapter that I've used is an ASUS Wireless N USB 2.0 Adapter that I purchased 3 of from Micro Center. They are being used on 3 Desktop Systems in a Commercial Office and have worked well in that application. Unfortunately that is stationary use application as the position of the systems and the router never changes. I used these so they would not project out to far from the case and get damaged or damage the motherboard if accidentally hit by the cleaning personnel.
Message was edited by: WoodyZ - Remove information about the ASUS Mini Bluetooth Dongle as it was not a WiFi Network Adapter. (Now to go have a cup of coffee.)