[Fedora-livecd-list] local hard disk space?

When I boot with Centos 5.1 Live CD, a df command shows the root filesystem / is mounted to /dev/mapper/livecd-rw and shows a total of about 4GB with 50% available. Is this disk space from my local hard drive? How is it carved out? My local hard drive is installed with a Windows XP system. Does LiveCD simply create a 4GB file on the local hard drive for its own use? --thanks, --Tony C. Coco Computers & Consulting http://coconets.homeip.net