When I install the GPMC on my XP workstation, it replaces the default Group Policy property sheet in AD Users and Computers with an Open button that requires me to launch GPMC. Is there any way I can undo this so that I can use the old GPO property sheet and still have GPMC as well?
Yes! In fact, when GPMC is installed, it registers new MMC property sheets for Group Policy tab within AD Users and Computers. However you can simply remove those new property sheet references from the registry and point it back to the old GPO property sheet. This won't affect GPMC functionality but will return the old GPO dialogs that you had before GPMC was installed. To make this change, you'll need to change the values under multiple keys, as follows (remember to back up your registry first in case you need to undo these changes):
In the first key,
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MMC\NodeTypes\{bf967aa5-0de6-11d0-a285-00aa003049e2}\Extensions\PropertySheet
delete the value that is there that refers to Group Policy Management and add a value with the following name, type and data:
{D70A2BEA-A63E-11D1-A7D4-0000F87571E3} REG_SZ = "Group Policy"
In the second key,
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MMC\NodeTypes\{bf967ab3-0de6-11d0-a285-00aa003049e2}\Extensions\PropertySheet
delete the value that is there that refers to Group Policy Management and add a value with the following name, type and data:
{D70A2BEA-A63E-11D1-A7D4-0000F87571E3} REG_SZ = "Group Policy"
The following additions to this item courtesy of Mika Seitsonen:
The following reg file can also be used to re-add the Group Policy tab to the domain, OU and site objects:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MMC\NodeTypes\{19195a5b-6da0-11d0-afd3-00c04fd930c9}\Extensions\PropertySheet]
"{D70A2BEA-A63E-11D1-A7D4-0000F87571E3}"="Group Policy"
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MMC\NodeTypes\{bf967aa5-0de6-11d0-a285-00aa003049e2}\Extensions\PropertySheet]
"{D70A2BEA-A63E-11D1-A7D4-0000F87571E3}"="Group Policy"
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MMC\NodeTypes\{bf967ab3-0de6-11d0-a285-00aa003049e2}\Extensions\PropertySheet]
"{D70A2BEA-A63E-11D1-A7D4-0000F87571E3}"="Group Policy"
Also, Mika notes, "And if you want to have both options and consequently two Group Policy tabs, just leave both values :)" meaning that you can have both the GPMC and old Group Policy tabs appear in AD U&C by simply not deleting the property sheet references to the GPMC.