First of all, thank you very much for your kind help.
I tried to create the same user name with same password in those 2 computers (one with WinXP and the other with Win2k) and made the same setting for TCP/IP
PC1: IP address 100.100.100.100
Subnet Mask 255.255.255.0
PC2: IP address 100.100.100.101
subnet mask 255.255.255.0
I also disabled the firewall. But it was still not working. Why?
Please help me more. Thanks a lot.