Hi Ron

 

I have tried to boot from the CD, but it just loops and reboots.

There is a hack that allows you to join MS media center to a domain, without having to reinstall it, that is done using the recovery console.

 

Insert Windows XP CD.
Start > Run > X:\i386\winnt32.exe /cmdcons
(replace X: with the appropiate drive letter)
Acknowledge prompt by clicking 'Yes'.
Skip updating process by clicking 'Cancel' or by pressing 'Esc'
After installation, acknowledge success msg. by clicking 'Ok'
Start > Shutdown > Restart
At boot menu, select 'Microsoft Windows Recovery Console'
Select proper installation to log onto (default: 1) and press 'Enter'
(If prompted, enter Administrator password and press 'Enter')
Type (without quotes) and press enter: 'cd system32\config'
Type (without quotes) and press enter: 'copy SYSTEM C:\'
Type (without quotes) and press enter: exit
At boot menu, select 'Windows XP Media Center Edition'
Log into Windows 
Start > Run > Type: 'regedit' and press enter
Click on 'HKEY_LOCAL_MACHINE'.
File > Load Hive...
Browse and select C:\SYSTEM
Specify key name 'BANANA' and click OK
Expand: HKEY_LOCAL_MACHINE > BANANA > WPA > MedCtrUpg
On the right-hand side, double-click IsLegacyMCE value
Change selected value to 1 and click Ok. (THAT IS NOT AN L!)
Click on BANANA subkey (under HKEY_LOCAL_MACHINE).
File > Unload Hive. Confirm.
Start > Shutdown > Restart
At boot menu, select 'Microsoft Windows Recovery Console'
Select proper installation to log onto (default: 1) and press 'Enter'
(If prompted, enter Administrator password and press 'Enter')
Type (without quotes) and press enter: 'cd \'
Type (without quotes) and press enter: 'copy SYSTEM C:\WINDOWS\SYSTEM32\CONFIG\SYSTEM'
(Yes, you want to overwrite - Go ahead and do it)
Type (without quotes) and press enter: 'del SYSTEM'
Type (without quotes) and press enter: 'exit'
At boot menu, select 'Windows XP Media Center Edition' 
Join domain.