If you have a client bridge based WiFi setup (Bullet, Nanostation etc.) plugged directly into LAN port on your laptop
, you can share the connectivity using your (redundant at this point) built in WiFi adaptor.
Instructions vary with Windows version but this is a good starting point. Select Network & Sharing Centre>Set up new connection or network, & follow instructions for creating adhoc wireless network. Add security
You then bridge the LAN adaptor to the WLAN adaptor. For Windows 7 & Vista go to Network and Sharing Centre>Manage adaptor settings & select/highlight LAN & Wireless adaptors. Right click on selection & choose Bridge option. Selecting this creates Network (MAC) bridge adapter. Note any adapter you choose must have Internet
sharing (ICS) turned off in order that it can be bridged.
Once created the bridge remains available for each network adapter. With the adapters bridged Internet
connectivity will be available to any other wireless device by simply connecting to the adhoc network you created.
The sharing can be achieved using ICS but I prefer this method as its more reliable, & you don't have to turn off sharing on each adapter when returning to normal use - just right click on bridge & select disconnect.
Note I have shared pay networks using this method which a certain professional supplier of WiFi devices claimed couldn't be done with client bridge.