XP Home on Win2000 Server Domain

I recently set up a client with a Win2000 Server domain. They have 7 machines all running WinXP Pro and all was well.

One of the users’ machines died, so he went out and bought his own machine running WinXP Home. He connected it to the network, named his machine the same as his old machine and logged into the domain with no problem. When he told me about it, I first stammered that XP Home will not work on a domain, but after checking his setup it sure looked like it was running fine.

I was hard pressed to explain to him why he should upgrade to XP Pro.

Anyone care to explain why he should or should not have to upgrade?

thanks

Nate