You may have to reinstall the drivers for you video and sound cards, also network card and any other hardware you have.
Do you have all the 'disks' that came with the computer that contain the drivers for these components?
How do I back up stuff? Can I simply make a copy onto a CD?
Yes backup all the data you want to save, programs you will have to reinstall.
Although I am the Adminstrator, I don't recall having issued myself a password. What if I did and I don't remember. Would I still be able to reformat and have future use of my computer?
You don't need it to reformat as far as I know and once you reinstall you won't need one to use the computer.
If I get stuck can I still contact you for help?
Yes just continue in this post, I'll keep it open
1) Are the terms "reinstalling the operating system" and "reformatting the hard drive" interchangeable?
reformatting wipes the hard drive clean and installing the OS is just what it says
2) I want to be able to reconnect to my ADSL line after reformatting and am concerned about how to reconfigure/reinstall all the relevant data.
I assume that you have a network card installed and that's how you connect to the internet. You may have to install the drivers for it.
If so you can just run the connection wizard , it should be listed under communications in your program files - see if you can find it.
Make sure you have you e-mail addresses
Open up OE > Tools > Accounts > Highlight you mail > Properties > Servers > record addresses for Incoming and outgoing mail.
NOWould they have installed a card in my computer?
Let me know, MrC