<p>How do I get a list of the active IP-addresses, MAC-addresses and <a href="http://en.wikipedia.org/wiki/NetBIOS" rel="nofollow noreferrer">NetBIOS</a> names on the LAN?</p>

<p>I'd like to get NetBIOS name, IP and <a href="http://en.wikipedia.org/wiki/MAC_address" rel="nofollow noreferrer">MAC addresses</a> for every host on the LAN, preferably not having to walk to every single PC and take note of the stuff myself.</p>

<p>How to do that with <a href="http://en.wikipedia.org/wiki/Windows_Script_Host" rel="nofollow noreferrer">Windows Script Host</a>/PowerShell/whatever?</p>

If you're using DHCP then the server will give you a list of all that information.
This website has a good tutorial on using powershell to get networking information
http://www.powershellpro.com/powershell-tutorial-introduction/powershell-scripting-with-wmi/
If you neet to get quick list of computer names you can use "net view".  Also have a look at nbmac although I'm unsure of it's working status under XP.  Another option could be to use nbtstat -a  (once you've used net view to list workstations)