Controlling 2 Windows 2k3 server computers using Windows XP mmc

Hi

I’ve recently created a workgroup from 3 test computers. 1 Windows XP computer and 2 Windows Server 2k3 computers under a test environment. I’ve assigned I.P’s to all 3,pinged and created a workgroup for all.
What I am trying to do is access the Windows 2k3 computers from My Windows XP computer using the MMC snap in tool under local users and groups. It recognized the computer however when I try and access, It comes up with the message ‘Access is denied’
I’m a total beguinner at this so any help would be appreciated.

Thanks