how to to remotely take ANOTHER computer command prompt without 3RD party softwaresIf your version of XP is "Professional" try this:

START>All Programs>Accessories>communications>Remote Desktop

type the IP address of the computer you wish to control.  Once you connect, just open a command prompt and DISCO!....you've got remote control of another computer WITHOUT third-party SOFTWARE (using a command prompt)...        Just be sure "remote desktop" is enabled in the FIREWALL exceptions, of the computer you with to connect to...BLOCKHEAD is correct & You will need proper credentials to connect username/password. If the nature of this is to hack peoples systems to try to get their command prompt as I was feeling that is not permitted and even with some flaws in the Terminal Services of specific Windows versions cracking them will not be discussed here.

Firewall exception will be required at port 3389 on the system to be managed if this is for non-malicious activity as well as RDP set up with specific users allowed for XP Pro or Windows Server 2000 or newer.

Also if this is to another site, port forwarding of port 3389 will have to be open for this system at the router at that site. If no router and direct connection to modem then your in with IP and credentials, and if router and router configured with port forwarding your in as well with proper credentials.