This is confusing to say the least - are you saying you have an XP machine which you would like to virtualise within Windows 7? If this is the case then maybe you could let us know your requirements, if you're looking for a quick and dirty approach, load up a remote session; however there are plenty of free virtual environments such as VirtualBox or Vmware Player available to you, getting the XP machine to these platforms of virtualisation is going to require a converter. Off the top of my head I know VMware provide a converter for physical machines to virtual formats to be imported into their player.
Following are links which will help you in achieving this:
( Will require signing up for their services, but its free and they dont hassle you)
VMware vCenter Converter, Convert Physical Machines to Virtual Machines
(be sure to read the documentation, or as a fall back let us know if you need help)