Windows XP includes a very useful tool for remote access which can allow you (or anyone else) to gain access to your computer and take control of it provided that you have permission to do so. To prevent brute force login attempts to your computer, disable Remote Access and consider shutting down port 3389 on your firewall.
You can of course change the port from the default 3389 to something harder to guess by scanners, such as 30123. To change the Remote Desktop listening port from 3389 to 30123, read Microsoft's own paper or do as follows.
Click start, run, type regedit and browse to
Find the "PortNumber" subkey and notice the value of 00000D3D, hex for (3389). Modify the port number in Hex and save the new value.
Alternatively, To disable Remote access via MSTSC (Microsoft Terminal Services Client), do the following:
1.) Right click on my computer, and choose "properties".
2.) Click on the "Remote" tab and remove the ticks if present in the checkboxes from "Allow Remotes Assistance invitations to be sent from this computer" and from "Allow users to connect remotely to this computer". Click ok to finish.