I got the info here from http://support.microsoft.com/default.aspx/kb/930056:
You experience installation errors and compatibility problems when you install Windows Server 2003 management tools on a Windows Vista-based computer
Download the Adminpak.msi for Windows 2003 Server SP1 from MS if you do not already have it on your network: click here to download it.
Once you have installed it and you run the ADUC you will get the following error:
MMC could not create the snap-in.
You will need to create and run the following CMD file. This will register all the DLL's needed for the Adminpak to run, you can just register them yourself but this may save you time.
cut and paste the following into a CMD file called Adminpak_vista.cmd for example.
@echo off
set filelist=adprop.dll azroles.dll azroleui.dll ccfg95.dll
set filelist=%filelist% certadm.dll certmmc.dll certpdef.dll certtmpl.dll
set filelist=%filelist% certxds.dll cladmwiz.dll clcfgsrv.dll clnetrex.dll
set filelist=%filelist% cluadmex.dll cluadmmc.dll cmproxy.dll cmroute.dll
set filelist=%filelist% cmutoa.dll cnet16.dll debugex.dll dfscore.dll
set filelist=%filelist% dfsgui.dll dhcpsnap.dll dnsmgr.dll domadmin.dll
set filelist=%filelist% dsadmin.dll dsuiwiz.dll imadmui.dll lrwizdll.dll
set filelist=%filelist% mprsnap.dll msclus.dll mstsmhst.dll mstsmmc.dll
set filelist=%filelist% nntpadm.dll nntpapi.dll nntpsnap.dll ntdsbsrv.dll
set filelist=%filelist% ntfrsapi.dll rasuser.dll rigpsnap.dll rsadmin.dll
set filelist=%filelist% rscommon.dll rsconn.dll rsengps.dll rsjob.dll
set filelist=%filelist% rsservps.dll rsshell.dll rssubps.dll rtrfiltr.dll
set filelist=%filelist% schmmgmt.dll tapisnap.dll tsuserex.dll vsstskex.dll
set filelist=%filelist% w95inf16.dll w95inf32.dll winsevnt.dll winsmon.dll
set filelist=%filelist% winsrpc.dll winssnap.dll ws03res.dll
for %%i in (%filelist%) do (
echo Registering %%i ...
regsvr32 /s %%i
)
echo.
Echo Command Completed
Browse to the folder where you saved the CMD file and then right click on it and select Run as administrator this will then go through and register the DLL's.
