Network PASSWORD?

I am trying to aid a friend with setting up a home network. The setup consists of 2 desktop computers, one running Win XP and the other Win ME. Also there is a laptop running Vista.

All is fine except...the two desktops can communicate OK (ie they can each access each others Files)but the laptop cannot access the files of the XP computer and the desktops cannot access the laptop files as a

Solved this...after much effort!! It is as simple as turning off the password within the Network System GUI on the Vista machine. Doh!!