Linux is able to read Windows partitions by mounting them onto the filesystem.
If you have a modern distro, your windows partiton was probably added when you installed. Try looking in the /mnt/ directory using your FileManager and see if there is a directory called 'windows' or similar. If so, then simply clicking on it should show the contents of your C drive.
If there is no such folder you will have to make one yourself.
Run (as root):
mkdir /mnt/windows
If you are running Windows 9x then runing
mount -t vfat /dev/hda1 /mnt/windows
from a terminal window as root should be enough to mount your C drive onto /mnt/windows where you can access it.
If you are running Windows 2000 or XP you will have to use
mount -t ntfs /dev/hda1 /mnt/windows
FedoraCore doesn't have NTFS drivers built into the kernel, so you can't read windows 2000 / XP drives with it. You can however install pre-compiled NTFS kernel RPMS for Fedora to make it work.
You can add the following to your /etc/fstab file to make your computer automatically mount the partition when you boot into linux. If you are using Windows 2000/XP replace the vfat with ntfs.
/dev/hda1 /mnt/windows vfat auto 0 0
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