I would like to add my Windows Media Center to my domain without having to reinstall. I went to the System Properties and the "Network ID" button is disabled, and when I click to change the name the Domain radio button is disabled allowing me to only change the Workgroup Name.

I checked online and the only solutions I found was to reinstall and specify to work on a domain. Please help me to add even if it is with a hack on the registry, I don't want to reinstall.

While is probably not the answer you're looking for, Microsoft designed Windows Media Center specifically for home use, which means that, like Windows XP Home edition, it has had the ability to join a domain removed. While you'll still be able to access network shares (using a domain username and password) you will not be able to use domain network log-ins or roaming profiles. For full Windows Domain support you'll either have to upgrade to Windows XP Professional or downgrade to Windows 2000.

there is registry key which is set during install, which tells windows domain or no domain. There is an instruction online on how to flip it from 0 to 1 to allow domain joining. Google it... But B4 u do anything, BACKUP your HARD DRIVE!!!

Right click on My Computer go to Properties

Click on the Computer Name Tab then click Change next to To rename this computer or join a domain, click Change.

From there under Member of click Domain: then enter the domain you want to join and when you join the domain it will ask for a username and password to make sure that you are authorized to join that domain and that's that you have joined the domain :)

When you go to logon it will give you the option to logon to the computer directly or on the to domain.