can't get 2000 machine to read xp pro machine

Hi,
Any advice would be great, thanks!!!
I have three machines.

A. work laptop w2k
B. home lap w2k
C. Home XP.

I am trying to get them communication. for some reason my
work machine (A) can't not access my other two machine.
it is connect to my LAN and is on the internet. when i
type in '\\andy' my machine name or type in the local ip
i get an error message saying they are accessable saying
there is no 'logon on servers avaiable to service my logon
request'.

My two home computers can communicate fine with each
other.

here is the wierd thing. computer B can access computer A
my work one. when i try to connect it prompts me for a
username and password. i enter my work info and i am
in. computer C my xp doesn't prompt with that login box
and thus not letting me in.

How can i get my laptop computer to access the other two?

Or how can i get my home XP computer to access my work lap?

can't get 2000 machine to read xp pro machine