The Remote Desktop connection settings for Windows Server 2008, and I believe Windows Vista, includes 3 levels of service:
- Don’t allow connections to this computer
- Allow connections from computers running any version of Remote Desktop (less secure)
- Allow connections only from computers running Remote Desktop with Network Level Authentication (more secure)

At first blush, you would probably choose the “more secure” option. Practically, this mainly means that it only allows connections from the latest Remote Desktop software in Windows Vista. It is probably another attempt by Microsoft to force consumers and businesses into upgrading to Windows Vista. But… I digress.
When connecting with an older Terminal Services (TS) client in XP or even Vista, you will get this message:
“Remote computer requires Network Level Authentication, which your computer doesn’t support”

Not all is lost. There are two ways around this. The first and most obvious solution is to select the less secure option and disabled Network Level Authentication (NLA). If you are in an environment that does not allow this change, or there are some other circumstances where you need to keep Network Level Authentication enabled, you can get a Remote Desktop connection from Windows XP.
The first step is to download the latest Remote Desktop Client for Windows XP. As of the writing of this article, the latest version is 6.1.
For XP SP3: here
For XP SP2: here
That is not it. For XP, you need to enable CredSSP – Credential Security Service Provider.
CredSSP is a new Security Service Provider (SSP) that is available in Windows XP SP3 by using the Security Service Provider Interface (SSPI). CredSSP enables a program to use client-side SSP to delegate user credentials from the client computer to the target server.
Directions on how do do this are available at Microsoft here:
http://support.microsoft.com/kb/951608/
The quick and dirty summary:
- Click Start, click Run, type regedit, and then press ENTER.
- In the navigation pane, locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
- In the details pane, right-click Security Packages, and then click Modify.
- In the Value data box, type tspkg. Leave any data that is specific to other SSPs, and then click OK.
- In the navigation pane, locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders
- In the details pane, right-click SecurityProviders, and then click Modify.
- In the Value data box, type credssp.dll. Leave any data that is specific to other SSPs, and then click OK.
- Exit Registry Editor.
- Restart the computer.
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Configure Network Level Authentication for Remote Desktop Services Connections
Network Level Authentication is an authentication method that can be used to enhance RD Session Host server security by requiring that the user be authenticated to the RD Session Host server before a session is created.
Network Level Authentication completes user authentication before you establish a remote desktop connection and the logon screen appears. This is a more secure authentication method that can help protect the remote computer from malicious users and malicious software. The advantages of Network Level Authentication are:
- It requires fewer remote computer resources initially. The remote computer uses a limited number of resources before authenticating the user, rather than starting a full remote desktop connection as in previous versions.
- It can help provide better security by reducing the risk of denial-of-service attacks.
To use Network Level Authentication, you must meet the following requirements:
- The client computer must be using at least Remote Desktop Connection 6.0.
- The client computer must be using an operating system, such as Windows 7, Windows Vista, or Windows XP with Service Pack 3, that supports the Credential Security Support Provider (CredSSP) protocol.
- The RD Session Host server must be running Windows Server 2008 R2 or Windows Server 2008.
Use the following procedure to configure Network Level Authentication for a connection.
Membership in the local Administrators group, or equivalent, is the minimum required to complete this procedure. Review details about using the appropriate accounts and group memberships at
http://go.microsoft.com/fwlink/?LinkId=83477
.
To configure Network Level Authentication for a connection
- On the RD Session Host server, open Remote Desktop Session Host Configuration. To open Remote Desktop Session Host Configuration, click Start, point toAdministrative Tools, point to Remote Desktop Services, and then click Remote Desktop Session Host Configuration.
- Under Connections, right-click the name of the connection, and then click Properties.
- On the General tab, select the Allow connections only from computers running Remote Desktop with Network Level Authentication check box.If the Allow connections only from computers running Remote Desktop with Network Level Authentication check box is selected and is not enabled, the Require user authentication for remote connections by using Network Level Authentication Group Policy setting has been enabled and has been applied to the RD Session Host server.
- Click OK.
The Network Level Authentication setting for an RD Session Host server can also be set in the following ways:
- During the installation of the RD Session Host role service in Server Manager, on the Specify Authentication Method for Remote Desktop Session Host page in theAdd Roles Wizard.
- On the Remote tab in the System Properties dialog box on an RD Session Host server.If the Allow connections from computers running any version of Remote Desktop (less secure) is not selected and is not enabled, the Require user authentication for remote connections by using Network Level Authentication Group Policy setting has been enabled and has been applied to the RD Session Host server.To configure the Network Level Authentication setting by using the Remote tab in the System Properties dialog box on an RD Session Host server, see Change Remote Connection Settings.
- By applying the Require user authentication for remote connections by using Network Level Authentication Group Policy setting.This Group Policy setting is located in Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Security and can be configured by using either the Local Group Policy Editor or the Group Policy Management Console (GPMC). Note that the Group Policy setting will take precedence over the setting configured in Remote Desktop Session Host Configuration or on the Remote tab.
To determine whether a computer is running a version of Remote Desktop Connection that supports Network Level Authentication, start Remote Desktop Connection, click the icon in the upper-left corner of the Remote Desktop Connection dialog box, and then click About. Look for the phrase Network Level Authentication supported in theAbout Remote Desktop Connection dialog box.