adrenaline

I have used the default setup when installing XP to connect two different XP machines. They see each other and work flawlessly. However, when I try to access my Windows 2000 machine, it does not see it, nor will that machine see the other two XP machines. I have tried enabled Netbios over TCP/IP setting to no avail, so in short, what gives? Any recommendations on the best way to make all 3 work together seemlessly?