You can use XP Pro or Home to access a server or other RDP host. Only XP Pro can act as an RDP Host. (on the client side. Server side Windows Server 2000 and Windows Server 2003 can too of course)
XP Home does offer Remote Assistance, but this is not the same as having the ability to make an RDP connection at will.
I hope you find this post helpful.
Regards,
Mark