If you want to manage Windows 2003 Active Directory from your local computer without having to RDP to the domain controller, then you must install the Windows 2003 Administration Tools Pack. This tool can be installed on Windows XP computer with SP1 and the proper hot fix knowledge base articel Q329357.
You can download the Windows 2003 Administration Tools Pack from Microsoft.com, just search for it. After you download it, run it and it will extract the file to a temp folder. Run the extracted file adminpack.msi, this will install the complete Administrative Tools under All Programs.