Newbie Question: How to boot from CD, and still access HD?

I have an old 486 computer that I have no use for, until I found Knoppix. I'd like to be able to still boot from the Knoppix CD, since I've heard that doing an HD Install really only makes it Debian. However, I'd still like to be able to save everything, preferences, email, etc. to the hard drive on the computer? Is that what the Home Persistant is? Or how would I do it?

Thanks in advance.

Edit: Also I've heard a lot about "remastering" the CD. What does this accomplish? And what can I do with it? Does it let me add programs to Knoppix? If not, how do I do that?

Once again, thanks for helping a Linux newbie, though if I can get these questions answered, I'm never going back to windows, save for some games and maybe photoshop.

I can't imagine that you'll be able to do much with a 486, but others feel free to speak up and prove me wrong. If you wan't to make the machine useful, you could use something like
Coyote Linux to turn it into a firewall/router.

Re. remastering, yes remastering lets you add/remove programs to knoppix and basically do whatever you want with it. Check out the howto in the docs section for info on how to do this.

I don't need to do much with the machine, and I know it runs Knoppix, as I just booted off the CD. What I want to know is can I make a partition on my HD that Knoppix can access and save everything to, and how big the partition needs to be.