[Problem] - Windows 7 ask for password if I access a Windows XP comput

Well there are 2 PC in my LAN: * NB * Notebook * WiFi connection to my router NETGEAR DGN2200v3 * Windows 7 Professional x64 SP1 * DSK * Desktop * Cabled connection to my router NETGEAR DGN2200V3 * Windows XP Home Edition 32bit SP3