802.1x authentication is more secure than Shared Key authentication and supports authentication and management through Internet Authentication Service (IAS) by using Remote Authentication Dial-In User Service (RADIUS). However, your Access Point (AP) must support 802.1x, and most inexpensive APs don't yet offer such support. Also, for centralized management, you typically must install and configure an authentication server to which you point the AP.
Because this security scenario requires an independent authentication mechanism (e.g., Extensible Authentication Protocol—EAP, RADIUS, certificates, smart cards, or username and password), it's stronger than simple Shared Key authentication. Also, 802.1x provisions RADIUS (or another authentication service) to send a dynamic key to both the client and the AP, thereby addressing a key 802.11b shortcoming: poor key management.