Access existing file system from CD

How are you trying to mount the partitions?

I'm new to Linux, not just Ubuntu. I expected the existing hard drive on my PC, currently WinXP, to be visible, albeit on a read only basis.
I have had access previously using a Knoppix3.9 CD, when the hard drive folders were all accessible.
Is it possible to mount drives when using a run from CD version of Ubuntu, or will I have to install it first?

The LiveCD does not support NTFS(which is most likely the format of the partition)

I've had success with the Dapper LiveCD (6.06 and 6.06.1) automatically detecting my NTFS partition and mounting it read-only. However, it does not appear on the desktop, even though it is mounted.

Note that by default it seems to only mount the first partition of the internal hard drive automatically.

Try Menu>System>Administration>Disks (available only on the Dapper CDs, I think it was removed in Edgy). You can pick a physical device from the left-hand column, and then click on the "Partitions" tab to see a list of the partitions on the drive. If the "Browse" button is active, click it to view an already-mounted partition.

If it is not, use the "Change" button next to "Access Path" to choose a location to mount it. You'll want to create a folder somewhere and pick that folder (browsing inside that folder will show the contents of the mounted disk). You should then be able to click "Enable" to make the disk mount, and "Browse" to open it.

This information is based on my experience and may not be correct or the best way to go about this. Does that help?