MrFixIt70 posted an answer for this D-Link ADSL2/2+ Modem/Wireless Router 4-Port Switch, 802.11g, QoS (DSL-2640B):
"Under your wirless tab. Make sure Enable AP is ticked. You have named your SSID, usually..."
MrFixIt70 posted an answer for this Microsoft Windows XP Professional With Servise Pack 2 (e8503040) for PC:
"This sounds like your original product key is either fake or has been hijacked and..."