To get a D: drive means you'll need another partition which can come from another hard drive or by creating a second partition on your current hard drive. 2 partitions on the same drive doesn't really create a separate backup in case of hard drive failure so some will get another physical drive and use that. So for example some people may go out and get something like a Maxtor OneTouch drive and use the software that comes with that drive to backup their machine. Others may just use that drive to hold files that they may want to transfer to various machines as some external drives are fairly portable.
Lastly, don't forget that there are various levels of backup from just burning certain files to a disc to creating a mirror of a hard drive's contents with something like Norton Ghost.
I have a windows xp media center edition, with a dell xps m140 notebook, with 60GB hardrive. I heard people say to have a c and d drive, so you can backup one of your hard drives to the other one. But I cant figure out a way to get a d: drive. What am I suppose to do? Also after I get a d: drive, how do you backup the c: drive to the d: drive? Also I recently purchased DVD-R's to backup my hardrive, but when I put the dvd in and go to the backup option in system tools, it says a need a removable storage service, so can I use the dvd's or do I need an external hard drive?