Ever take a late night call from a user who is trying to remote into their office computer and you need to enable RDP remotely so they can get in remotely? Assuming a domain environment it is pretty easy. This was easy in Windows XP, you could remote connect to the registry and turn it on. Win 7 blocks that.
For Windows 7-
From the server,
psexec \\machinename reg add "hklm\system\currentcontrolset\control\terminal server" /f /v fDenyTSConnections /t REG_DWORD /d 0
One minor issue, this doesn’t poke a hole in the windows firewall. You’ll need to temporarily disable it, log in, add RDP to the profile, then turn it back on. From the server-
netsh -r ComputerName -u Username -p Password -c advfirewall set allprofiles state off
That will shut off the firewall. You can now RDP into the box and open RDP in the GUI in Windows Firewall, then turn it back on.
For Windows XP-
Just go into Regedit, File, Connect Network Registry. Once connected go to HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server
Change fDenyTSConnection to 0
If you need to turn off windows firewall, you can go to Computer Management, connect to the box, and stop the windows firewall service. (DO NOT attempt this in Windows 7).