How to visit every computer on the network and modify the hosts file in windows xp

Depending on what you are trying to do will determine greatly what the real answer is. If you want the powershell script to run on the remote machine and you want the user to be able to run it. Your only option is to have credentials embedded into the script. This is dangerous and should not be done.

If you can launch the scripts remotely, your options become much better. In Powershell V2 you have remoting as an option to complete many tasks which will use the rights of the user running the script (i.e. the admin) on the target machine (the user's PC). In V1 you have the option of launching the script remotely via PSExec to use the credentials of the Admin. You also have the option of running the script on the Admin's PC and building it to interact with the remote machine via WMI/PSExec/etc.

The short answer to your direct question is No you cannot do that. However, you can accomplish the same thing by approaching it from a slightly different angle.

Here's a batch file for you:

@echo off
rem Loop thru list of computer names specified on command-line
for /f %%i in (%1) do call :check_machine %%i
goto end

:check_machine

rem Check to see if machine is up.
ping -n 2 %1 >NUL 2>NUL
if errorlevel 1 goto down

rem Reverse-lookup machine name and report
for /f "usebackq tokens=2" %%d in (`ping -n 1 -a %1 ^| find "Pinging"`) do echo %1:Up:%%d
goto end

:down
rem Report machine down
echo %1:Down

:end

Pass it a text file with a list of computer names in it and it'll PING them (2 tries-- you can increase that by increasing the number after "-n" on the 1st PING command-line), and if it gets a response, perform a reverse-lookup of the name. It returns results as:

computer-name-1:Up:name-it-resolved-to
computer-name-2:Down
computer-name-3:Up:name-it-resolved-to
...

To run multiple in parallel, just make multiple text files w/ different lists of machine names and launch a few copies in parallel.

Quick and dirty saves the day.