Your password - actually the security key - may be right but the level of security is wrong. Try adding the network manually as a Preferred Network in XP in the left hand pane of the View Wireless Ntworks form or in Vista and Windows 7, under Control Panel>Network and Sharing Centre>Manage Wireless Networks.
I just had this problem. Old software is WPA..you need WPA2. Download Service Pack 2 than download Hot Fix KB893357at Microsoft or other web sight. That did the trick for me. After that download click wireless network and reconnect with your normal password.