First off, welcome to the forums!
Hmm, how does it connect to send footage?
USB or Firewire for example?
You maybe find if its new enough, it'll have Firewire. If not, it might be standard USB or even USB 2.0 which is slightly faster. As its XP, it should automatically configure the camera using windows drivers to have it going straight away.
You'd then need a capture program.
If you have Windows XP which you will have on that Media Centre PC, find Windows Movie Maker, which is a simple editing tool, and Capture the video using that.
It makes the process rather easy for you
If you want, download from the Windows website the update to the program which updates it, called Movie Maker 2, and when installed, replaces the old one.
Hopefully this will help as a start