If you don't care about your data and don't need to back anything up, you can reinstall windows straight from the disc you have. If you do care about your data, you'll have to hook up another drive. Unfortunately, it seems like your problems are beyond the point of just hooking up a drive and copying files.
I'll give you two parts. First, how to reinstall windows. Second, how to copy files. Once again, if you care about your data you should skip down to the second part now.
1. Put your windows cd into your drive and reboot. Your screen should pop up with a message that says "Press any key to boot to cd." If it does not, reboot again, and this time go to your Setup screen. This is usually done by pressing the "F2" key or "DEL" key initially upon booting. Once you are in your setup screen, you need to change the Boot order to go to CD before it goes to Hard Disk.
Once you've booted up to your cd, you will be run through a windows installer that will let you partition and reformat your computer to do a new installation of windows.
2. The best way to copy your files when your hard disk fails or you can't recognize drives is to run a live version of linux.
Ubuntu is what I use. Don't be scared now! Linux is very user-friendly, graphical, and easy to navigate these days. You don't need to know any code to run it or use it. You will need to download Ubuntu Linux on another machine and burn the CD, as I assume your computer won't handle downloading and burning a cd image. Once you have your Ubuntu CD, all you do is reboot with it in your drive and choose to Try the live version of Ubuntu. This will not take up any hard drive space and it won't overwrite your files. Ubuntu will simply be running in your memory space and allow you to access your computer and external drive so you can backup your files.
Good luck!
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