partitioning is necessary/okay, but I have a few questions
 

I now understand that partitioning is both necessary and desirable, and that I therefore must learn about it, which will take some work, but I have one or two basic questions.

1) As I modify the Linux operating system, can I copy it to another partition, then boot from the copy? Can I make a CD copy of my new modified operating system, and boot from that? Can I continue this process back and forth erasing previous versions until I get the operating system and the CD exactly the way I want it? Can I do this with both Linux, and also with Windows?

2) Someone suggested obtaining a separate external hard drive, but the Setup options on my computer don't seem to include this. There are just three choices, floppy, internal CD drive, and internal hard drive. How would one enable external drives as boot options? Can one do that?

I and others could benefit tremendously, and save a lot of time and expense, with insight from those who are experienced with these issues!

It would take a little work, but you can copy to another partition. You need to change the boot-loader so that it points to where your /boot is. You need to change your /etc/fstab so the system know where all your partitions are located. Might be more, but that's what I can think of at the moment.

I don't think you could move it to a bootable CD. There are distros that run off a LiveCD, but it took years to get them running, and they are special systems.

As long as Windows stays on the first partition of the drive, it should be happy.

If you create a boot-floppy, with mkbootdisk, then you might be able to boot to an external drive. You might need to edit some files on the floppy to point it to the external rather than the internal.

Standard Warning: Anytime you edit the partitions, there is the chance you could lose everything on the drive. Back up anything you really really need to keep safe.

In the end, it might be safer / easier / quicker to back-up data / files to CDs, wipe the drive, and start over.

Concerning the question of an external hard drive, why don't you just purchase another internal hard drive and play with Linux there until you are satisfied? That's what I've been doing for a few months now. Until I get all my hardware recognized, sound working properly, the applications installed that I want, the system properly configured and secured, I'm using my other hard drive for my important work, and the second hard drive for learning Linux. That way there's not much to lose if I hose the Linux system (which I've done a few times) and my important data is safe on the other hard drive. Additionally, you would probably be getting an USB external drive, and your Linux kernel may not have USB support configured out of the box.

NB: Do not automount your main hard drive, as I did that and one day while I was working in Linux, all of a sudden I heard one of my hard drives churning away for about 60 seconds. I tried to find out what was happening, but not knowing enough about the Linux system, I couldn't. The next day when I booted into the other OS, I found that D:\ had been formatted. I lost about 17GB of data. So, I don't automount my other drives in Debian anymore until I have Debian secured properly.

Another option you may want to consider is Knoppix, which uses Debian GNU/Linux and runs from a CD using a ramdisk. I have been toying with it on my laptop, and just installed the newest Knoppix v3.3 to that hard drive. It has support for a lot of hardware, has a lot of applications included, and is much easier to install and runs much faster than RedHat, for instance. Now I'll recompile the kernel to remove the support for hardware I don't need and optimize Knoppix for my laptop. I think it's a nice way to jump into a stable, running Linux system when you don't really know a lot about Linux.