Wi-Fi

• How can I find the physical address (MAC address) of the built-in wireless network interface of my VAIO computer?
• What should I do if I cannot connect my VAIO computer to an access point (or the Internet)?
• What should I do if I cannot play back movies or audio tracks received via Wi-Fi(R) (Wireless LAN), or their playback is interrupted? Why is the data transfer speed slow?
• What should I do if I cannot use the Wi-Fi(R) (Wireless LAN) function?
• What should I do if I do not know the SSID or security key for the access point?