Moving C:\Users to another partition on Windows Server 2008 Standard

Windows XP profiles are not compatible with Vista profiles out of the box.

Microsoft has a whitepaper Managing Roaming User Data Deployment Guide which includes a section called 'Windows Vista and Windows XP Roaming User Profile Interoperability'.

I haven't tested this, I hope it will be useful. I suggest you read the full document for more details.

Quoting from that document:

Configure the Documents folder to interoperate between Windows Vista and Windows XP

1. Log on to a domain computer running Windows Vista with domain administrator credentials. Open the Run command by pressing the Windows logo key + R. Type GPMC.MSC, and then click OK.
2. Right-click a New Group Policy object or a Group Policy object that has a previously enabled Folder Redirection policy, and then click Edit. For example, in the Contoso.com domain, there is a policy named "Folder Redirection Policy."
3. Under User Configuration, double-click to expand Windows Settings and Folder Redirection. Right-click the Documents folder, and then click Properties.
4. If you have deployed a folder redirection policy setting for the Documents folder, then use the path and setting defined in that policy setting. If not, then use the Redirect to the following location policysetting with a path that is not included in the user profile
5. Click the Settings tab. Select the Grant the User Exclusive rights to Desktop;Move the contents of Desktop to the new location; and Also apply redirection policy to Windows 2000, Windows 2000 Server, Windows XP, and Windows Server 2003 operating systems check boxes.

Update: The original question was for Windows Server 2008, but the solution is easier for Windows Server 2008 R2 and Windows Server 2012 (and Windows 7 and 8). You can add the user through the NTFS UI by typing it in directly. The name is in the format of IIS APPPOOL\{app pool name}. For example: IIS APPPOOL\DefaultAppPool.

IIS APPPOOL\{app pool name}

Note: Per comments below, there are two things to be aware of:

• Enter the string directly into the "Select User or Group" and not in the search field.
• In a domain environment you need to set the Location to your local computer first.

Reference to Microsoft Docs article: Application Pool Identities > Securing Resources

Original response: (for Windows Server 2008) This is a great feature, but as you mentioned it's not fully implemented yet. You can add the app pool identity from the command prompt with something like icacls, then you can manage it from the GUI. For example, run something like this from the command prompt:

icacls c:\inetpub\wwwroot /grant "IIS APPPOOL\DefaultAppPool":(OI)(CI)(RX)

Then, in Windows Explorer, go to the wwwroot folder and edit the security permissions. You will see what looks like a group (the group icon) called DefaultAppPool. You can now edit the permissions.

However, you don't need to use this at all. It's a bonus that you can use if you want. You can use the old way of creating a custom user per app pool and assigning the custom user to disk. That has full UI support.

This SID injection method is nice because it allows you to use a single user but fully isolate each site from each other without having to create unique users for each app pool. Pretty impressive, and it will be even better with UI support.

Note: If you are unable to find the application pool user, check to see if the Windows service called Application Host Helper Service is running. It's the service that maps application pool users to Windows accounts.