the remote computer requires network level authentication which your computer does not support xp

how to fix windows RDP client

To fix windows 7 or XP SP3 clients do the following


• Configure Network Level Authentication


1. Click Start, click Run, type regedit, and then press ENTER.

2. In the navigation pane, locate and then click the following registry
subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

3. In the details pane, right-click Security Packages, and then click Modify.

4. In the Value data box, type tspkg. Leave any data that is specific to other SSPs, and then click OK.

5. In the navigation pane, locate and then click the following registry
subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders

6. In the details pane, right-click SecurityProviders, and then click Modify.

7. In the Value data box, type credssp.dll. Leave any data that is specific to other SSPs, and then click OK.

8. Exit Registry Editor.

9. Restart the computer.
http://technet.microsoft.com/en-in/library/cc732713.aspx