Thanks for all the suggestions.
rjbinney, can you walk me through the security setting, I don't hnow that much about WinXP, thanks.
Doc, all three machines are using the same gateway-192.168.2.1 For security reason, I disabled the DHCP server on the router and assigned static IP for each computer, my W2k laptop is 192.168.2.2, W2K desktop is 192.168.2.3 and my housemate's WMe is 192.168.2.3,
which by the way, is not part of my LAN and the WinXP is 192.168.2.4.