Remote Desktop Connection
I must admit I've been a hard-core VNC man for many years, but in recent times have come to appreciate the Windows Remote Desktop Connection (RDC) feature. It's easy to use and integrates the two systems (the controller and the controlled) in ways which VNC cannot. To use it, the feature must be enabled on the host PC (the one which will be remotely accessed).
Configuring an XP host
To enable RDC under XP, go to Control Panel | System | Remote tab | Remote desktop and tick 'Allow users to connect remotely to this computer'. Next click the 'Select Remote Users' button, click the 'Add button', click 'Advanced button', click the 'Find now' button and click on a username who will be authorised to control this workstation. Click OK, OK, OK OK.

Configuring a Vista host
To enable RDC under Vista, go to Control Panel | System | Remote settings (top left of box) | Remote tab and tick 'Allow connections from computers running any version of Remote Desktop'. Next click the 'Select Users' button, click the 'Add button', click 'Advanced button', click the 'Find now' button and click on a username who will be authorised to control this workstation. Click OK, OK, OK OK.

Remote controlling from XP or Vista
Basically Remote Desktop is a part of the Microsoft Windows Terminal Server feature set and hasn't changed much from XP to Vista. You can start the remote control session Start | RUN (Windows key + R) and typing mstsc (Microsoft Terminal Server Client).

The next window just requires a computername to connect to, but clicking on the 'Options' button reveals a number of extra options, like remembering your username and password..

Once in the RDC session, a small menu appears at the top of the guest workstation's screen. This allows minimisation or closing of the remote session window..

Note that when the guest RDC user is logged on, the host workstation will lock the current user out (their programs will still be running however) and they won't be able to view what's happening. If the host workstation user unlocks their workstation it will kick the remote user off and log them out.
The process of connecting to another computer is identical from XP and Vista..
