If, despite these warnings, you still want to use WEP shared key authentication, you can do so by following these steps:

To manually create a network profile using WEP shared key authentication
Click to open Network and Sharing Center.

Click Set up a new connection or network.

Click Manually connect to a wireless network, and then click Next.

On the Enter information for the wireless network you want to add page, under Security type, select WEP.

Complete the rest of the page, and then click Next.

Click Change connection settings.

Click the Security tab, and then, under Security type, click Shared.

Click OK, and then click Close.