Yes, no and maybe.
Because of the way Windows works, it is difficult to make an exact copy of your main drive onto another drive. It will not copy the Windows system files and often programs files. So without special software, you can not make a complete copy of your main drive.
But you don't need to. That is because if the main drive crashes, you can use a Windows CD to reinstall Windows. And you can use your original disk to reinstall your other programs. All you really need to copy is your data. That is things like your music, pictures, documents, videos, etc.
One trick to to allows save your data somewhere inside your "My Documents" folder. Then to do a backup, all you need to do is copy that one folder to your second partition. All the subfolders and files in it will come along.
Should the main drive crash because of Windows going bad, you reinstall Windows and copy back your data.
However should the hard drive fail mechanically, you would be unable to access the second partition and everything would be lost. Usually when doing this, it is better to use a second hard drive or an external drive rather than a partition on the same drive.
Another alternative is to copy your backup to DVD(s) so that if the drive fails, you have a way to recover the data.