IIRC, this comes switched on in XP Pro, (I dunno about Home). To all intents it's Terminal Services with a cuter name.....
Actually- you are thinking of Remote Desktop...

Q. Is Remote Assistance the same thing as Remote Desktop?

A. No, it isn't. Remote Assistance uses Remote Desktop technology to allow an expert to provide assistance to a novice user on a computer running Windows XP. Get more information about Remote Assistance .
They are virtually the same, but Remote Desktop does not exist on XP Home. You are right that it is like Terminal Services- basically to let tech support or the HelpDesk access your system and do what they need to do. That is partially why it doesn't exist in XP Home. In XP Home you would have to use Remote Assistance and actually send the email invitation in order for someone to access your system remotely.

Q. Is Remote Desktop available on Windows XP Home Edition?

A. No, however you can upgrade from Windows XP Home Edition to Windows XP Professional to get Remote Desktop. You can use Windows XP Home Edition as the client for accessing your Windows XP Professional computer running Remote Desktop.