I do not believe that MMC is available in XP Home. And nor do I think you can download the administration pack for it. What you can do is right click on my computer and select 'Manage' this will take you to something similiar where you can manipulate users.

May I also suggest investing in XP Professional, although both carry the title of 'XP', Home and Pro are two completely different animals. I'd like to say Home Edition is nothing more than a 'beefed' up version of ME.

As to the erroring out when you try to access the control panel, it sounds like a DLL has been hijacked (not uncommon spyware behavior). You might want to look into downloading Spybot SD and just giving the system a quick once over to see what it discovers. I'd be interested in knowing what you come up with.

Best of luck, and work on upgrading