XP Media Center & XP Pro "upgrade"

I recently purchased 3 HP slimline media centre PC's which are loaded with XP media center. We got them to use in our shop and it was the small size of the units which attracted me to them.
They setup fine, but we then found they would not go on a domain, so I went and purchased the last 3 XP Pro upgrade packages from a local wholesaler.
We then found out you cannot "upgrade" XPMC to XP Pro, as it is considered a downgrade.
The wholesaler will not give me a refund, so it appears I've done my money on the upgrades, unless there is some type of work around to be able to load XP Pro onto these machines.
I have 4 old Windows 2000 original CD's which are no longer installed on any computers in our business, so I guess I could legally load them onto the new PC's and then upgrade them, but I'd like to know if there is an easier way to do it.

 

Welcome to WindowsBBS AlaninAdelaide

You can join a domain with Media Center ....... requires a registry hack. I've done it, and it works.

http://blog.tiensivu.com/aaron/archives/29-Join-a-domain-with-Windows-Media-Center-Edition.html

 

Oops ........double post. Since I'm here again anyway, I may as well mention that if you have MiniPE or BartPE to load the system hive, you can load and edit it from there as opposed to using the recovery console/copy system hive/reboot/load hive/edit/unload/reboot to RC/copy method described in the link.