If you want to use a long range WiFi USB adapter such as the Alfa AWUS036H or the Rokland n3 with your laptop, and you have a WiFi card built in, you will need to disable that card in order to use the USB adapter for Internet access. Likewise, when you want to go back to using your internal card, you need to enable it.
Doing this is a simple process in Windows Vista. If your laptop has an external on/off switch for the internal WiFi card, it is pretty self explanatory. But if not, what you want to do is click on Start and go to Control Panel. Change to icon view and double click the Network and Sharing Center icon. On the window that comes up, click on Manage Network Connections. There you should see your internal ethernet adapter displayed in icon format as Local Area Connection. Then you should see your internal WiFi adapter as Wireless Network Connection. Your external USB WiFi adapter should appear as Wireless Network Connection 2. To be sure which icon corresponds to which device, just mouse over the respective icon and a little box will appear telling you to what hardware device the Wireless Network Connection icon corresponds.
Once you have located the icon that corresponds to your internal WiFi card, right click on it and select Disable. To re-enable the card, repeat the same steps and select Enable. You can also mouse over the Wireless Network Connection icon that corresponds to your external USB WiFi adapter and select the Connect/Disconnect option to connect to available access points.