Hardware Technician

i have PCs with Windows XP sp2 OS,a laptop with Vista bussiness and the domain controller has windows 2000 server OS. so the vista PC cant see other computers but the rest of PCs can see it.
what could be the problem help me. i have tried a lot of things that includes re-configuring the active direcotory, re-laying of cables and termination etc but to no avail. please assit me resolve this problem.