Access your desktop remotely with this handy built in feature of Windows XP / Windows Server
Remote Desktop Connection is an incredibly handy utility allowing a user to login in to their desktop from a remote location (whether this is the other end of the building or the other side of the world it works the same!)
If you are accessing a computer via the internet you will, of course, need a secure way of accessing the network through the internet - the obvious one is via VPN but this sort of connectivity will not be covered here as it is a full topic in itself and is not even required if the PC you are in is on your local network (for example, you may want to access a server without having to get to it).
So, lets begin:
Please note that you must be logged in as an administrator to carry out the follow tasks.
In order for a remote user to be able to login to your computer, you need to make sure that Remote Desktop is enabled on your computer and that the user logging in has the right to do so (administrators automatically have access when Remote Desktop is enabled).
To enable Remote Desktop on your computer, go to the Control Panel and double click "System" (see below). If you can't see it, your control panel is probably in "Category View", click the "Switch to Classic View" link on the left of your control panel to switch.

Next, click on the "Remote" tab and check the box "Allow users to connect remotely to this computer" (see below)

Next click, "Select Remote Users" - you will be presented with a box like the one below, here you should see your name below the white square, saying "John Doe already has access". If you can't or you wish to allow other users to access your computer, click add and follow the prompts, if not, click OK and OK again and thats it - Remote Desktop is enabled on your PC! Note that Administrators are granted access by default once you enable Remote Desktop.

To access a remote computer using Remote Desktop Connection, you need to know either its IP address or a name that points at its IP address (such as a domain name). On your computer, go to START > Programs > Accessories > Communications > Remote Desktop Connection. You will be prompted with a box like the one below, enter the IP address or name for the computer you wish to connect to and click "Connect". You will be prompted for your username and password - entering it will log you securely in to the target computer.