Password protect D-Link wireless router DSL-2640U

Security options to choose from.

Wired Equivalent Privacy (WEP) - Less secure (The key can be recovered from network sniffing)
Wi-Fi Protected Access (WPA and WPA2) - The recommended solution to WEP security problems.
WPA-PSK (Pre-shared key mode) is the personal mode which is designed for home and small office network setups.
WPA supports two encription methods to choose from.
TKIP - Temporal Key Integrity Protocol.
AES - Advanced Encryption Standard which is considered to be fully secured.


Seting up a security key (password)
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Type http://192.168.1.1/ in your browser to open the router admin console.
Go to the wireless security tab and choose the follwing settings for each
option.
Network Authentication: WPA-PSK
WPA Pre-Shared Key (Password): Combination of numbers and letters.
WPA Group Rekey Interval: 0
WPA Encryption: AES
WEP Encryption: Disabled.

Following is a screenshot of the required settings.

Adding the wireless network password to Windows Vista

Setingup the password in Windows Vista can be done throught the "Manage Wireless Networks". Access "Manage Wireless Networks" from Control Panel>Network and Sharing Center>. Right click and select properties of the DLink network. Select the security tab and enter the following.
Security type: WPA-Personal
Encryption type: AES
Network security key: (Enter the previousely setup password)




Now your wireless network is fully protected.